Chapter I: II. III. IV. V (2)

The anterior zygapophyses and metapophyses maintain a nearly constant position close to the top of the centra throughout the column, from the seventh thoracic backward, and are vertical, thin, and oblong, squared or rounded. They begin to decrease in size noticeably on the first caudal, and on the seventh caudal are mere swellings at the sides of the nearly horizontal plate from which the neural spine springs. They are traceable as far as the twelfth caudal.

A ridge appears on the side of the neural arch near its base on the fifth caudal and is stronger and very marked on those following, to the ninth caudal. A ridge unites the anterior and posterior facets for the chevrons on the ninth and succeeding caudals.

_Barnegat City_ (female).—Unlike the Newport skeleton, there are no neural spines on the fifth, sixth, and seventh cervicals. The spine on the first thoracic vertebra is quite short and sharp, and on the second, third, and fourth thoracics also is rather pointed, though of increased length. There is no metapophysis on the seventh cervical.

On the seventh thoracic the facet for the tubercle of the rib, instead of being very prominent, becomes inconspicuous. The metapophysis is flat and squared, and there is no lower facet on the side of the centrum. On the eighth thoracic the metapophysis is thin, squared, and vertical, and a well-formed transverse process appears on the side of the centrum. The transverse processes of the ninth thoracic are a little curved backward, and on the first lumbar and succeeding vertebræ bent forward. These processes are less tapering on all the lumbars than in the Newport skeleton. They disappear on the eighth caudal. None is perforated.

The longest neural spine is on the sixth lumbar, and on all the lumbars both the anterior and posterior edges are somewhat convex. Hence their shape is rather different from those of the Newport skeleton, in which the anterior margins are somewhat concave. The tips of the spines are rather suddenly expanded. The spines of the caudals are rather more expanded at the tip and more inclined backward than in the Newport skeleton. They disappear on the eleventh caudal.

The horizontal plate joining the metapophyses is noticeable on the fifth caudal. The ridge on the side of the neural arch is first noticeable on the fourth caudal and is very strong on the fifth, sixth, and seventh. The metapophyses are last traceable on the twelfth caudal.

_Charleston_ (female, jr.).—This skeleton resembles the Newport one as regards the facets for the articulation of the tubercles of the ribs, except that the seventh thoracic resembles the sixth and has no lower facet on the side of the centrum. The transverse processes of the ninth thoracic are rather strongly curved backward, while those on the last thoracic and first lumbar are nearly straight. On succeeding vertebræ they are inclined forward. They are last traceable on the eighth or ninth caudal (vertebra 35 or 36). None is perforated by a foramen.

Though the vertebræ are defective, there appear to have been no neural spines on the fourth to the seventh cervicals, inclusive. The spine on the first thoracic is short, and on the first to the fourth is pointed. The spine disappears on the tenth caudal (vertebra 37).

The metapophyses assume the vertical position on the eighth thoracic. The last of these processes is barely traceable on the tenth caudal (vertebra 37). The ridge on the side of the neural arch is well marked on the fifth to the ninth caudals, inclusive. On the seventh caudal (vertebra 34) the anterior and posterior facets for the chevrons are united on the right side, and on the eighth caudal and succeeding vertebræ on both sides.

CERVICAL VERTEBRÆ.

_Barnegat City_ (female).—The first four cervicals are united. The foramen above the anterior articular facets of the atlas is complete, and the edges of these facets are raised. The inferior lateral process is flat, broad, and strongly bent backward.

Second cervical: Inferior lateral process nearly as long as that of the first cervical; broad, flat, and bent backward parallel with the process of the first cervical. Superior lateral process short, strong, and flat. A large incomplete foramen between it and the inferior process.

Third cervical: A short, conical inferior process, curved forward.

Fourth cervical: Similar, but with smaller and shorter inferior process. Neural arch and spine complete; the latter fused with the preceding spines. Arch not reducing the size of the neural canal.

Fifth cervical: Arch and spine broken. Arch nearly as broad as the anterior epiphysis of the centrum. Inferior lateral process short, straight, and directed obliquely outward.

Sixth cervical: Spine broken. Arch complete, nearly as wide as the anterior epiphysis. Inferior lateral process short, thick, knobbed, and directed obliquely outward and a very little forward. The left longer.

Seventh cervical: Spine obsolete. Arch complete, as wide as the anterior epiphysis. No superior lateral process or metapophysis. A thick articular facet for the head of the first rib on the middle of the side of the centrum. No inferior lateral process.

Fused spines of the first to fourth cervicals bent backward; the mass broad antero-posteriorly and rounded at the tip.

_Newport_ (male).—First cervical with the foramen over the anterior articular facets incomplete, and the borders of the facets less raised. The facets also broader and more declined. Inferior lateral process thicker, somewhat tapering, and nearly transverse.

Second cervical: Inferior lateral process much shorter than that of first cervical, about parallel with it, but with the tip bent forward. Superior lateral process short, thick, and bent backward; joined to the inferior process on the right side, inclosing an oval foramen.

Third cervical: A short, straight, triangular superior process on the right side; that on the left short and blunt. Inferior lateral process long, thick, club-shaped, and curved backward.

Fourth cervical: Inferior lateral process similar to the last in shape, but shorter, broad and flat, and only slightly curved backward. Neural arch and spine separate from those of the third cervical; the arch rather smaller than those preceding it, and reducing the size of the neural canal.

Fused spines of the first to third cervicals nearly vertical, rather high, and obtusely pointed.

Fifth cervical: Spine pointed and quite long. Arch complete. Inferior lateral process short, squared, flattened, and directed outward obliquely.

Sixth cervical: Spine about as long as on the fifth cervical. Arch much narrower than the anterior epiphysis. Inferior lateral process prominent, thick, somewhat compressed, and directed downward.

Seventh cervical: Spine as high as the arch, obtusely pointed. Arch complete, as wide as the anterior epiphysis. A strong conical superior lateral process, or metapophysis, on a broad base, directed forward. An articular raised facet on the side of the centrum, directed obliquely backward. No inferior lateral process.

_Charleston_ (female, jr.).—The first to fourth cervicals resemble those of the Newport skeleton, but the fourth entirely separate. All the lateral processes undeveloped, or broken off, except the right inferior lateral process of the atlas, which is like that of the Newport specimen. The anterior foramen of the atlas is incomplete, as in that specimen, and the spines of the conjoined vertebræ are vertical and pointed. (Pl. 25, fig. 1.)

Fifth cervical: Spine wanting. Arch complete. Inferior lateral process undeveloped, or abraded.

Sixth cervical: Spine and processes broken. Arch wide.

Seventh cervical: Similar to that of the Newport skeleton, but the spine obsolete or broken.

THORACIC VERTEBRÆ.

_Barnegat City_ (female).—First thoracic: Spine vertical, pointed, about as high as arch and centrum together. A moderately long process with articular facet for tubercle of rib on side of neural arch; facet elliptical and directed a little downward and forward. A smaller facet for head of second rib on posterior upper edge of centrum.

Seventh thoracic: Metapophyses long, extending horizontally, straight superiorly. A small articular facet on the outer side near the base, directed downward; strongest on right side. A very small facet on posterior upper edge of centrum, scarcely noticeable on right side. Neural spine rather narrow at tip; superior margin straight.

Eighth thoracic: Metapophyses squared and thin. A distinct transverse process on side of centrum about half as broad as the centrum is long, and as long as centrum is broad; flattened, squared, and a little curved backward and upward. Articular facet for rib elliptical and directed obliquely backward. A broad, shallow groove across base of transverse process, the anterior edge of which is emarginate proximally. Neural spine as in seventh thoracic.

Ninth thoracic: Metapophyses squared. Transverse process similar to that of eighth thoracic, but equal to centrum in length, little narrowed at base, and directed outward; anterior edge convex, posterior concave; articular facet occupying the posterior half of the distal edge. A very shallow groove proximally.

_Newport_ (male).—First thoracic: Neural spine a little curved backward and rounded at tip; much higher than length of arch and centrum together. Articular facets as in Barnegat skeleton.

Seventh thoracic: Metapophyses similar in shape to those of Barnegat skeleton but with a very distinct facet on side of arch, terminating a process about as long as the greatest diameter of the facet; surface of facet rugose. Below this process, on side of centrum, a very large, oval, sessile facet, reaching forward nearly to the anterior face of the centrum and upward to its superior edge. A very low, small swelling on the posterior superior edge of centrum, probably indicating the point of attachment of a cartilage connecting the head of the eighth rib. Neural spine expanded at free end, and superior margin rounded.

Eighth thoracic: Metapophyses similar to those of Barnegat skeleton. A distinct transverse process nearly as broad as the length of the centrum, oblong or squared, flat, directed somewhat backward, but not upward. Articular facet for rib not occupying whole of free end and only slightly directed backward; anterior margin as in Barnegat skeleton. Neural spine similar to that of seventh thoracic.

Ninth thoracic: Similar to that of Barnegat skeleton, but transverse process longer than centrum and directed a little downward, articular facet occupying less than posterior half of free margin; proximal groove inconspicuous; anterior and posterior margins nearly straight.

_Charleston_ (female, jr.).—The centra of the thoracic, as well as the lumbar, vertebræ in this individual present inferior median keels, and more or less concave sides, which is not the case in the Barnegat and Newport skeletons. This can not be due to immaturity, as in a still younger individual, supposed to represent _Ziphius grebnitzkii_, the thoracic vertebræ are rounded below. The neural spines of the thoracic vertebræ are much less inclined backward in _semijunctus_ than in the Newport and Barnegat skeletons, but this is doubtless connected with age, as the younger series of vertebræ already mentioned exhibits the peculiarity in a more marked degree. A similar modification dependent upon age appears to affect _Hyperöodon_, as will be seen by comparing Van Beneden and Gervais’ figures in the Osteography, plate 18.

First thoracic: Similar to that of Newport skeleton, but spine not higher than arch alone. (A little abraded at tip, but probably undeveloped.)

Seventh thoracic: Metapophyses short (abraded), incompletely developed. A distinct facet on side of same on an elongated process, as in Newport skeleton, but no second larger one on side of centrum. No facet on superior margin of centrum either anteriorly or posteriorly.

Eighth thoracic: Transverse process similar to that of Barnegat skeleton, but anterior edge nearly straight; process about one-half as broad as length of centrum. (Indications of immaturity.)

LUMBAR VERTEBRÆ.

_Barnegat City_ (female).—First lumbar: Similar to last thoracic, but transverse process expanded distally and slightly directed forward; a little longer than centrum; anterior and posterior edges emarginate proximally.

Eleventh lumbar (last): Centrum very long. Neural arch and spine very high, more than twice length of centrum. Spine inclined backward much beyond posterior face of centrum; anterior margin straight, posterior convex, tip expanded. Transverse process a little more than one-half length of centrum, somewhat expanded at distal end and curved forward so that tip is about in line with anterior face of centrum. Metapophyses close to centrum and to each other, semihexagonal in outline. A sharp median inferior ridge, and shallow posterior oblique channels on under side of centrum.

_Newport_ (male).—First lumbar: Similar to that of Barnegat skeleton, but transverse processes considerably longer than the centrum and not expanded at tip; anterior edge straight, posterior only slightly emarginate proximally.

Tenth lumbar (last): Centrum like that in Barnegat skeleton. Neural arch and spine only slightly higher than length of centrum. Transverse process oblong, free margin nearly transverse; process inclined forward so that tip is a little beyond anterior face of centrum. Metapophyses close to centrum, rounded in outline. Neural spine much inclined backward; anterior edge concave, posterior convex, tip expanded. A rounded inferior median ridge and very distinct oblique posterior channels on under side of centrum.

_Charleston_ (female, jr.).—First lumbar: Similar to that of Barnegat skeleton, but transverse process directed outward and scarcely or not at all forward; length of process equal to that of centrum; tip rounded (due to immaturity).

Tenth lumbar (last): Centrum very long. Neural arch and spine a little less in height than length of centrum. Transverse process oblong, curved forward, more than one-half as long as centrum. Metapophyses similar to those of Newport skeleton. Inferior median ridge very sharp; lateral channels rather indistinct.

CAUDAL VERTEBRÆ.

_Barnegat City_ (female).—First caudal (vert. 28): Similar to last lumbar, but neural spine broader antero-posteriorly. Transverse process ࡪ length of centrum, inversely triangular, the tip much in advance of anterior face of centrum, free end somewhat rounded. Metapophyses similar to those of last lumbar. No median inferior ridge, but two short processes bearing facets for chevrons posteriorly and a very slight indication of similar process anteriorly, but without facets. Posterior inferior oblique channels indistinct.

Seventh caudal (vert. 34): Centrum (exclusive of chevron processes) nearly as deep as long. Neural arch and spine only a little higher than length of centrum, very much inclined backward and expanded at distal end; free border of spine straight. Metapophyses close to centrum, united nearly to tips by a horizontal plate. A ridge extends backward from their tips nearly across the arch. Another very prominent ridge traverses the centrum at the base of the arch. At the posterior end, a deep groove, convex forward, extends down the side of the centrum, making an emargination in the transverse process and proceeding thence down the lower side of centrum to its lower middle point, where it ends in a deep semicircular emargination between the anterior and posterior chevron facets. Transverse process a triangular stub, reaching nearly to the line of the anterior face of centrum. Chevron processes very large, and the median inferior surface of the centrum between them deeply grooved longitudinally.

Tenth caudal (vert. 37): Centrum as deep as long. Neural spine a low ridge, as long as the centrum, and extending beyond it posteriorly. No transverse processes. A foramen in side of centrum much above the middle and a similar one below. Close to the latter and below it another foramen pierces the ridge uniting the chevron processes, and appears below on side of longitudinal inferior median channel. Metapophyses small mammilliform processes on top of centrum.

Eleventh caudal (vert. 38): No processes. A very small neural spine. Posterior epiphysis strongly convex.

Twelfth caudal (vert. 39): A rounded mass without processes.

Thirteenth caudal (vert. 40): An oblong mass, with two grooves on each side, two widely separate foramina above and two closely approximated below, entering a common depression, with rounded projections on its borders.

Fourteenth caudal (vert. 41): Similar to thirteenth caudal, but with a single lateral groove.

Fifteenth caudal (vert. 42): Similar to fourteenth caudal, but sides extending upward and downward in a ridge. Inferior foramina nearly as far apart as superior and posterior epiphysis much smaller than anterior.

Sixteenth caudal (vert. 43): Similar to fifteenth caudal, but the disproportion of epiphyses greater and lateral ridges higher. Superior and inferior surfaces of centrum inclined.

Seventeenth caudal (vert. 44): Similar to preceding, but smaller.

Eighteenth caudal (vert. 45): Longer than high. Inferior ridge longer and larger than superior. Groove very large. Anterior face of centrum deeply concave, posterior flat. Posterior epiphysis very much smaller than anterior. Foramina very small, practically obliterated on right side.

_Newport_ (male).—First caudal (vert. 27): Similar to last lumbar, but transverse process shorter, about two-thirds as long as centrum, oblong and but little constricted at base; distal margin nearly straight. The process does not extend forward quite to the line of the anterior face of centrum. No inferior median ridge, but strong posterior chevron processes. Postero-inferior oblique grooves very distinct.

Seventh caudal (vert. 33): Similar to the same vertebra in Barnegat skeleton, but neural spine more inclined backward and anterior border deeply concave. Metapophyses oblong, directed upward, not reaching anterior face of centrum as they do in Barnegat skeleton. Anterior face of centrum receding superiorly and the ridge opposite it on side of centrum shorter than in Barnegat skeleton. Ridge behind metapophyses indistinct. Postero-inferior oblique grooves as in Barnegat skeleton, but piercing transverse process, forming a foramen. Anterior and posterior chevron processes very large and receding very much, as do also the anterior and posterior faces of centrums.

Eleventh caudal (vert. 37): Similar to Barnegat skeleton, but spine shorter than centrum and not extending beyond it anteriorly or posteriorly. Metapophyses similar, but wider apart.

Twelfth caudal (vert. 38): Neural arch barely complete. No spine.

Thirteenth to nineteenth caudals (vert. 39-45): Similar to those of Barnegat skeleton.

Twentieth caudal (vert. 46): Rudely triangular, with a peg-like posterior projection, bearing the very small posterior epiphysis. No foramina. Anterior epiphysis deeply concave in middle.

_Charleston_ (female, jr.).—First caudal (vert. 28): Similar to last lumbar, but only a faint inferior median ridge. Inferior outline of centrum antero-posteriorly very concave, which is not the case in the Barnegat and Newport skeletons. Posterior chevron processes prominent. Postero-inferior oblique grooves shallow.

Seventh caudal (vert. 34): Like the Newport skeleton. The transverse process not pierced or emarginate. Postero-inferior oblique grooves indistinct. Ridges on centrum very distinct. Right anterior and posterior chevron processes united and pierced by a foramen.

Tenth caudal (vert. 37): Similar to the same vertebra in Newport skeleton, but neural spine very short.

CHEVRONS.

The number of chevrons in the North American and some other specimens is as follows:

Newport, Rhode Island. 11
Barnegat City, New Jersey. 8(+3?)
Charleston, South Carolina. 8+
Buenos Ayres, Argentina (Burmeister). 11
Holma, Sweden (Malm). 9
Littleton Harbor, New Zealand (Haast). 10
Warrington, New Zealand (Scott and Parker). 9
Pisa Museum (Van Beneden). 9

The chevrons are similar in form in the three North American specimens, with some differences which will be pointed out below.

_Newport_ (male).—The first chevron consists of a pair of bones which are not united. They are longer than deep, their depth indeed being less than that of any one of the succeeding bones except the tenth and eleventh. Each presents one strong superior articulating facet. Second chevron, elongated antero-posteriorly, but not much deeper than the first. Third chevron very deep and only equaled in that respect by the fourth; narrowed and rounded off below. Fourth chevron largest and broadest (antero-posteriorly) of the series; expanded below and the lower border transverse. Fifth to eighth similar in form, but less deep successively, and the lower border more rounded. Ninth similar to eighth, but smaller and thinner. Tenth similar to first, longer (antero-posteriorly) than deep. Eleventh similar to tenth in form, but smaller.

_Barnegat City_ (female).—First chevron bone lacking. Second like that of Newport skeleton, but smaller. Third similar to second, but much larger and more produced posteriorly; quite unlike the third in the Newport skeleton in form, and much less deep. Fourth, largest and deepest of the series; anterior and posterior borders rounded, and the inferior border similar. Fifth to eighth similar in form, but successively less deep, and all more expanded below; inferior border nearly straight. Ninth similar to eighth, but depth not exceeding breadth; lower angles produced.

_Charleston_ (female, jr.).—The chevrons of this specimen resemble those of the Newport skeleton, but on account of immaturity they are all more or less rounded. The two sides of the first chevron are united. The second is without the posterior angular projection seen in the other specimens. The third is the deepest of the series. The eighth is not deeper than long, and hence resembles the tenth chevron of the Newport skeleton in proportion, but is, of course, much smaller. Two or three chevrons are lacking from the posterior end of the series.

RIBS.

_Barnegat City_ (female).—First rib shortest and broadest, but considerably broader at proximal end than at distal end. Head and tubercle close together. The succeeding ribs increase in length and decrease in breadth to the fifth or sixth. The third, fourth, and fifth are expanded and flattened at distal end. Seventh, eighth, and ninth successively shorter. Distance between head and tubercle greater on second rib than on first, and on third is greater than on second. On the third to sixth, inclusive, the distance is about equal. The tubercle is scarcely distinguishable on the seventh rib, while on the eighth and ninth it is lacking, these ribs joining the transverse processes by a terminal facet only.

_Newport_ (male).—Similar to those of the Barnegat skeleton, but first rib maintains nearly the same breadth throughout. Neck thicker than in Barnegat skeleton. Seventh rib terminates proximally in a single large rugose facet, which connects with a similar facet on side of centrum of seventh thoracic vertebra.

_Charleston_ (female, jr.).—Similar to those of the Barnegat skeleton, but a distinct tubercle on the seventh rib. Eighth and ninth ribs end proximally in a transverse facet only, which is largest on the eighth. Tenth rib (represented by a fragment) only half as broad as the preceding ones and more nearly round in section.

STERNUM.

_Barnegat City_ (female).—Five segments. Manubrium wider than long, convex inferiorly. Deep anterior and posterior notches, about equal, the former with an angular projection on each side. Facet for cartilaginous sternal rib thick and prominent. Second segment wider than long, about equally notched anteriorly and posteriorly, the two sides anchylosed together by a bony bridge, about as wide as the notches are deep. Third and fourth segments similar to second but smaller; similarly notched; left portion a little longer than right. Fifth segment elongated, left side very much so; the two sides joined by a narrow bridge; posterior notch very deep.

_Newport_ (male).—Similar to sternum of Barnegat skeleton, but manubrium scarcely wider than long; posterior notch much longer than anterior, with parallel sides. Second and third segments similar to those of Barnegat skeleton but sides of latter not completely anchylosed together. Fourth segment in two pieces, with a wide interval between. Fifth segment triangular with deep anterior, triangular notch, a narrow bridge, and short posterior prolongation (the left longer than the right).

_Charleston_ (female, jr.).—Resembles the sternum of the Barnegat skeleton rather than that of Newport skeleton, but anterior parts cartilaginous. Opposite sides of second, third, and fifth segments anchylosed together and those of fourth segment nearly so. (Pl. 25, fig. 2).

SCAPULA.

_Barnegat City_ (female).—Superior border irregular. Posterior angle acute. Anterior and posterior borders nearly straight. Ridges distinct. Acromion broad both at base and at tip, sharply bent upward, so as to be parallel with anterior border of scapula. Coracoid nearly as long as acromion, slender, a little curved upward, irregular and somewhat expanded at the end.

_Newport_ (male).—Superior border irregularly rounded. Posterior angle obtuse, anterior angle projecting. Ridges indistinct. Anterior and posterior borders nearly straight, but irregular. Acromion broad at base, tapering toward the tip, which is again somewhat expanded; bent upward, but not sufficiently to be parallel with anterior margin of blade. Coracoid rather thick, irregular, strongly expanded at tip.

_Charleston_ (female, jr.).—Rather too much abraded for comparisons, but posterior margin more concave than in either of the other skeletons.

FORE LIMB.

_Barnegat City_ (female).—Fore limb much shorter than in the Newport skeleton. Humerus: Head quite oblique, the lower edge overhanging the shaft considerably on the ulnar side. Tuberosity level with upper surface of head, elliptical in outline when viewed from above. Deltoid ridge moderately prominent, irregular, rugose, and extending to about the middle of the shaft. Distal end of humerus not expanded. Bicipital groove inconspicuous.

Radius: Almost perfectly straight, but a little inclined toward ulna at oblique proximal end; scarcely expanded at distal end, which is lower externally than internally.

Ulna: Much slenderer than radius, rounded triangular in section, not expanded at distal end, where the margin is lowest externally. Olecranon well developed, thin, and pointed proximally.

Carpals: Five; two on ulna side, two median and one on radial side in line with first metacarpal. The proximal middle bone (intermedium) extends much farther proximally than those on each side of it.

Metacarpals: Metacarpal III longest, metacarpal II broadest. Metacarpal I oblong, or rather conical, with a lateral enlargement, and situated in line with the distal row of carpals.

Digits: First phalange of first digit short and conical.

_Newport_ (male).—Fore limb considerably longer and more massive than that of the Barnegat skeleton but similar otherwise, except as follows:

Humerus: Head rather larger and less inclined. Deltoid ridge more prominent.

Radius: Broader proximally and rounded at distal end, where it extends outward beyond the carpal bones.

Ulna: Thicker, and olecranon less pointed.

Carpal bones: Middle carpal bone not extending farther proximally than those on either side of it.

Metacarpals: Metacarpal I nearly square, third longest, second to fourth more constricted.

Digits: First phalange of first digit long and cylindrical. Phalangeal formula: I, 1; II, 6; III, 6; IV, 4; V, 2.

Measurements of the skeletons above described are as follows:

_Dimensions of four skeletons of Ziphius cavirostris._

Column headings:
A: Barnegat City, New Jersey. 20971 U.S.N.M. female, adult.
B: Newport, Rhode Island. 49599 U.S.N.M. male, adult.
C: Charleston, South Carolina. 21975 U.S.N.M. female, young.
D: Bering Island. (Vertebræ) young.

Measurements. A B C D
mm. mm. mm. mm.
Length of skull 945 915 797 ...
First to fourth cervicals (vert. 1-4):
Length of combined centra 81 79 66 55
Greatest breadth of atlas 283 259 210(?) 146
Greatest height of atlas 215 218 170 148
First thoracic vertebra (vert. 8):
Greatest breadth 211 220 174(?) 122
Greatest height[a] 267 321 163 133
Length of centrum 42 46 32 19
Height of centrum 70 67 48 49
Seventh thoracic vertebra (vert. 14):
Greatest breadth 142 158 147 128
Greatest height 440 417 260 182
Length of centrum 102 103 74 51
Height of centrum (ant.) 68 69 49 44
Eighth thoracic vertebra (vert. 15):
Greatest breadth 253 288 177 100
Greatest height 447 427 265 186
Length of centrum 110 109 78 54
Height of centrum 65 69 51 47
Ninth thoracic vertebra (vert. 16):
Greatest breadth 329 366 248(?) 122
Greatest height 418 431 277 192
Length of centrum 117 117 82 58
Height of centrum 69 75 53 49
First lumbar vertebra (vert. 17):
Greatest breadth 385 393 [b]275 142
Greatest height 464 451 [b]293 200
Length of centrum 122 120 [b]89 62
Height of centrum 74 81 [b]55 50
Tenth lumbar vertebra (vert. 26):
Greatest breadth 362 335 [c]230 158
Greatest height 524 488 [c]343 242
Length of centrum 172 162 [c]129 85
Height of centrum 107 109 [c]78 71
First caudal vertebra (vert. 27):
Greatest breadth 336(?) [d]313 223 166
Greatest height 483 [d]458 307 235
Length of centrum 178 [d]160 127 91
Height of centrum 113 [d]109 81 75
Seventh caudal vertebra (vert. 33):
Greatest breadth 164 [e]161 113 110
Greatest height [f]255 [f]250 155 [f]135
Length of centrum 139 131 103 77
Height of centrum (ant.) [f]111 [f]119 [f]85 [f]78
Twelfth caudal vertebra (vert. 38):
Greatest breadth 90 [g]88 61 62
Greatest height 83 [g]78 53 61
Length of centrum 55 [g]56 46 47
Fifteenth caudal vertebra (vert. 41):
Greatest breadth 64 [h]62 49 45
Greatest height 54 [h]52 33 30
Length of centrum 42 [h]39 30 28
Eighteenth caudal vertebra (vert. 45):
Greatest breadth 37 [i]38 ... ...
Greatest height 20 [i]19 ... ...
Length of centrum 24 [i]22 ... ...
Twentieth caudal vertebra (vert. 46):
Greatest breadth ... [j]25 ... ...
Greatest height ... [j]13 ... ...
Length of centrum ... [j]19 ... ...
Chevrons:
Antero-posterior length of first ... 74 ... ...
chevron
Depth of same ... 66 44 ...
Length of second chevron 83 107 55 38
Depth of same 87 85 74 63
Length of third chevron 114 91 61 46
Depth of same 135 206 123 90
Length of fourth chevron 125 122 67 51
Depth of same 213 206 111 67
Length of eighth chevron 80 86 43 35
Depth of same 108 115 41 33
Length of ninth chevron 84 74 ... 27
Depth of same 83 88 ... 19
Scapula:
Greatest length 385 415 [k]224 159
Greatest height 275 300 175 132
Length of acromion [l]115 159 ... 48
Length of coracoid from edge of glenoid 127 148 60 38
Pectoral limb:
Total length 588 652 ... ...
Humerus:
Length 168 177 130 95
Breadth at distal end 69 69 52 42
Radius:
Length [m]178 [m]175 [m]135 ...
Breadth at distal end 55 65 41 ...
Ulna:
Length without olecranon 165 171 118 ...
Length including olecranon 220 225 150 ...
Breadth at distal end 44 42 30 ...
Metacarpals:
Length of first 31 28
Length of second 52 55
Length of third 52 58
Length of fourth 44 51
Length of fifth 37 39
Phalanges:
Length of first phalange of first digit 27 44
Sternum:
Total length [n]803 821 [o]550 [o]395
Length of manubrium 259 306 [o]203 105
Breadth of manubrium 286 333 193 128
Length of fifth segment [o]170 [p]184 [o]128 [p]92
Breadth of fifth segment 133 168 86 82
Ribs:
Length of first rib (straight) 405 410 277 191
Breadth of first rib at proximal end 88 110 65 46
Breadth of first rib at distal end 63 80 40 30
Length of fifth rib (straight) 785 770 545 415
Length of ninth rib (straight) 620 620

[a] The measurements of height of vertebræ are from center of inf.
margin of centrum to center of tip of spine, unless otherwise
specified.
[b] Last thoracic.
[c] Ninth lumbar.
[d] Second caudal = vert. 28.
[e] Eighth caudal = vert. 34.
[f] Without chevron facet.
[g] Thirteenth caudal = vert. 39.
[h] Sixteenth caudal = vert. 42.
[i] Nineteenth caudal = vert. 45.
[j] Vert. 46.
[k] Edges abraded.
[l] A little broken.
[m] In median line.
[n] Without cartilages.
[o] With cartilages.
[p] Left side.

PHALANGEAL FORMULA.

The formulas for the ossified phalanges in two American[39] and three Old World specimens are as follows:

_Phalangeal formula of five specimens of Ziphius cavirostris._

Locality. I. II. III. IV. V.
Newport, Rhode Island 1 6 6 4 2
Barnegat City, New Jersey 1 6 6 4 3
Villefranche, France (Haeckel) 1 5 6 4 2
Pisa Museum, Italy (Van Beneden) 1 3(?) 5 4 1
Warrington, New Zealand (Scott and Parker) 1 5 5 4 2

SUMMARY OF DIFFERENCES IN SKELETONS.

The chief differences between the Barnegat City and Newport skeletons are in the size and form of the processes of the cervical vertebræ, the form of the seventh and eighth thoracic vertebræ and of the ribs connected with them, the direction of the acromion of the scapula, the shape of the first phalange of the first digit, and of the posterior segments of the sternum. As far as the processes of the cervicals are concerned, these are known to be extremely variable in all cetaceans. The seventh and eighth thoracic vertebræ are those on which the mode of attachment of the ribs changes in ziphioid whales, and I have observed in the genus _Mesoplodon,_ as here, that the processes and articular facets were very variable, being sometimes quite unlike on the two sides of the same vertebra. The direction of the acromion is probably subject to large individual variations, though this can not be determined at present, and the same is true of the form of the first phalange of the first digit. The form of the sternum is quite variable in all cetaceans, and can not be relied on for specific characters, without comparison of many individuals.

On the whole, I am of the opinion, as already stated, that we are not compelled by the differences noted to regard the Barnegat and Newport skeletons as representing different species. The Charleston skeleton is too young and imperfect to admit of serious consideration. The idea that the differences between the adult skeletons are probably individual receives support from the fact that the skeleton shown in the photograph from St. Simon Island, Georgia, mentioned on page 31, No. 14, appears to possess a combination of characters exhibited by the other two.

AGE VARIATIONS IN SKULLS.

The series of skulls of _Z. grebnitzkii_, which the Museum owes to the activities of Dr. L. Stejneger and Mr. N. Grebnitzki, comprises specimens of different ages, and, as will be shown presently, probably both sexes. Taken together with the skulls from the east coast of the United States they probably represent very fully the variations which the skull undergoes in the present species. These changes may, perhaps, be best made evident by the following brief descriptions of the various skulls:

_21975. Charleston, South Carolina._—Young female. (Type of _Z. semijunctus_.) All sutures open, and elements of occipital bone distinguishable. No mesethmoid ossification. Opposite maxillary notches, premaxillæ closely approximated, nearly flat and horizontal, and about level with adjacent parts of maxillæ. Left premaxilla grooved longitudinally at this point. Orifice of anterior nares on a level with lower end of rectangular projecting boss formed by superior portion of nasals. Rostrum pointed, much broader distally than it is deep. A very distinct rudimentary alveolar groove in distal end of each maxilla. Proximal end of vomer resting against anterior face of nasals and reaching up to overhanging boss. Anterior face of the latter nearly flat. (Pl. 14, fig. 1; pl. 18, fig. 1; pl. 20, fig. 1; pl. 21, fig. 2.)

Rami of mandible not anchylosed together at symphysis. Teeth hollow, open at the root, acute at apex, tipped with enamel; diameter 10 mm. (Pl. 22, fig. 1; pl. 24, fig. 1.)

_20971. Barnegat City, New Jersey._—Adult female. Majority of sutures open, but those on superior surface of rostrum between maxillæ and premaxillæ partly anchylosed. Vomer nearly all anchylosed to rostral portion of premaxillæ; it presents a slight median elevation, but there is no mesirostral ossification. Right premaxilla in front of nares broad, flat, and horizontal; left, nearly so, but with a quite broad longitudinal groove. Opposite maxillary notches premaxillæ nearly on a level with adjacent parts. Orifice of anterior nares level with lower end of nasal boss. End of rostrum quite acute, and broader than deep. Rudimentary alveolar groove distinct distally. Proximal end of vomer anchylosed with anterior face of nasals and reaching up to nasal boss, which has a sharp median ridge completing nasal septum superiorly. Anterior face of nasal boss slightly concave on each side of median line. (Pl. 14, fig. 2; pl. 18, fig. 2; pl. 20, fig. 2; pl. 21, fig. 3.)

Rami of mandible anchylosed together at symphysis and suture largely obliterated. Teeth slender, cylindrical, rugose, rather blunt; roots closed; diameter 13 mm. (Pl. 24, fig. 3.)

_22069. Bering Island._—Adult female? All the sutures about as in preceding specimen. Mesirostral ossification distinct, rounded, extending from base of rostrum nearly to apex, but disappearing before reaching line of anterior ends of maxillæ. Its upper surface below that of premaxillæ. Premaxillæ approximated, and right premaxilla with an angular process near base of rostrum overlapping mesirostral ossification. Premaxillæ at base of rostrum, anterior nares, proximal end of vomer, and nasals as in preceding skull. Apex of rostrum moderately acute, broader than deep. Rudimentary alveolar groove shallow. (Pl. 15, fig. 1.)

Rami of mandible anchylosed together and suture largely obliterated. Teeth somewhat fusiform, blunt; roots closed; diameter, 14 mm. (Pl. 22, fig. 3.)

_83991. Bering Island._—Similar in all respects to preceding, but mesirostral ossification a little less well developed.

_22874. Bering Island._—Entirely similar to two preceding, but premaxillæ a little curved out from mesirostral ossification and left premaxilla opposite maxillary notch rather strongly inclined, nearly vertical. Anterior face of nasal boss distinctly concave. (Skull defective.)

_21246. Bering Island._—Sutures as in three preceding skulls. Mesirostral ossification distinct and rounded, but much below level of premaxillæ. Rostral portion of premaxillæ narrow and widely divergent toward base of rostrum, leaving mesirostral entirely exposed. Right premaxilla on a line with maxillary notches strongly concave and sunk below level of maxillæ. Left premaxilla vertical, with a broad groove. Right premaxilla remains low and concave proximally, the posterior end being then abruptly turned upward and reaching level of vertex. Orifice of anterior nares on a level with lower end of nasal boss, and vomer resting against anterior face of nasals, which latter have a median ridge continuing nasal septum, but with a slight vacuity between the two. Rudimentary alveolar groove nearly obliterated. Outer sides of premaxillæ at distal end strongly concave. Rostrum rather acute, about as deep as wide opposite distal ends of maxillæ. (Pl. 15, fig. 2.)

_20993. Bering Island._—Adult male? (Type of _Z. grebnitzkii_). Majority of sutures open, but maxillæ and premaxillæ anchylosed together above and on the sides. Premaxillæ approximated anteriorly, but diverging posteriorly. Mesirostral ossification well developed, reaching level of premaxillæ; anteriorly rather narrow but a little broader near middle of rostrum, where it is beveled off abruptly. Behind this point premaxillæ strongly concave, nearly vertical and widely separated, forming a large and deep basin, in the bottom of which the vomer appears as a broad, irregular bony surface. Bottom of basin much below level of surrounding parts. Orifice of anterior nares much below level of nasal boss. Vomer reaching lower end of nasals. Anterior face of latter strongly concave, with only a moderate median ridge completing nasal septum above. Mesirostral with a median groove at distal end. Premaxillæ high at distal end, but sides nearly plane. Rostrum compressed near apex, deeper than wide. (Pl. 16, fig. 1; pl. 19, fig. 1; pl. 20, fig. 3.)

Rami of mandible anchylosed together and suture partly obliterated. Teeth conical, with rather short, acute tips; roots closed, short and conical; diameter, 25 mm. (Pl. 23, fig. 1; pl. 24, fig. 2.)

_21245. Bering Island._—Nearly all sutures between maxillæ and premaxillæ at end of rostrum, above and below, anchylosed together, but majority of others traceable. Condition of superior surface of skull very similar to that of preceding, but premaxillæ rather low at distal end. Mesirostral at distal end rather lower than premaxillæ and concave superiorly; more posteriorly assuming form of a narrow ridge, with a deep channel between it and premaxillæ on each side. More posteriorly still it widens rapidly, with a convex surface, and terminates abruptly with a truncated end, the surface of which is concave. A deep basin around nares, as in preceding skull. Orifice of anterior nares far below level of nasal boss. The latter largely absorbed and deeply undercut and concave in front. Nasal septum terminating before reaching lower end of nasals, and ridge on latter low and traversing left nasal. Sides of premaxillæ at distal end very concave. Rudimentary alveolar groove nearly obsolete. Rostrum blunt at apex, and about as deep as wide at anterior ends of maxillæ. (Pl. 16, fig. 2.)

_21248. Bering Island._—Similar to preceding, but mesirostral ossification higher than premaxillæ at distal end and convex above; less abruptly widened posteriorly and posterior termination flat. Narrow, deep grooves between ossification and premaxillæ on each side, or, in other words, premaxillæ more closely approximated to sides of mesirostral distally. Basin around nares and conformation of the several bones bordering it similar to preceding. Sides of premaxillæ concave at distal end, the grooves thus formed in them intruding some what on the maxillæ, especially posteriorly. Apex of rostrum very blunt, rounded off below and projecting above; deeper than wide. Rudimentary alveolar groove nearly obsolete. (Pl. 17, fig. 1; pl. 22, fig. 4.)

Rami of mandible anchylosed together and the symphysis and suture largely obliterated. Teeth very broadly fusiform; tip short and rather blunt; roots closed; diameter 30 mm.

_49599. Newport, Rhode Island._—Adult male. All sutures on superior surface of skull more or less anchylosed together. Mesirostral ossification and premaxillæ all on one level near apex of rostrum, but at extreme tip mesirostral lower, forming a narrow ridge with a deep groove on each side between it and premaxillæ. The same conformation repeated more posteriorly, but grooves deeper and wider, while mesirostral maintains the same level as premaxillæ. It widens suddenly here, forming a broad flat-topped mass, which is a little overlapped by the premaxillæ. The mass terminates suddenly somewhat behind middle of rostrum with a deep concavity placed obliquely. Basin in front of the nares and conformation of bones composing it as in two preceding skulls. Vomer at proximal end touching lower end of nasals, and nasal septum continued behind and above it as a low ridge, composed of the inner edges of the two nasal bones and reaching up to the nasal boss. Outer sides of premaxillæ near distal end deeply concave. Apex of rostrum rather blunt, deeper than wide opposite distal ends of maxillæ; all the bones anchylosed together, but some of the sutures indicated by grooves. Rudimentary alveolar groove nearly obsolete. (Pl. 17, fig. 2; pl. 19, fig. 2; pl. 21, figs. 1, 5.)

Rami of mandible anchylosed together at symphysis, the suture indicated only by a groove. Teeth large, broadly conical and tapering at the tip. Root very short, rugose, conical and closed; diameter 29 _mm._ (Pl. 22, fig. 2; pl. 23, figs. 2, 3.)

The dimensions of the several skulls are as follows:

_Dimensions of ten skulls of Ziphius cavirostris (including the types
of Z. grebnitzkii Stejneger and Z. semijunctus Cope)._

Column headings:
A: 83991. Bering Island. _grebnitzkii._
B: 21248. Bering Island. _grebnitzkii._
C: 22874. Bering Island. _grebnitzkii._
D: 21246. Bering Island. _grebnitzkii._
E: 20993. Bering Island. Type _grebnitzkii_.
F: 22069. Bering Island. _grebnitzkii._
G: 21245. Bering Island. _grebnitzkii._
H: 21975. Type _semijunctus_.
I: 20971. Barnegat, N. J. Female, _cavirostris_.
J: 49599. Newport, R. I. Male, _cavirostris_.

Measurements. A B C D E F G H I J mm. mm. mm. mm. mm. mm. mm. mm. mm. mm. Total length 900 877 [a]807 850 963 882 855 797 945 915 Length of rostrum 491 480 [a]397 470 550 480 476 463 550 514 Height from vertex to 433 450 ... ... 515 471 481 349 440 465 inferior border of pterygoids Distance from tip of rostrum 664 670 ... ... 735 682 673 614 735 726 to posterior free margin of pterygoids (median) Distance from the same to 617 621 [a]538 600 690 623 589 590 708 676 anterior end of nasals Breadth between centers of 495 513 [b]499 488 563 [b]486 492 393 476 530 orbits Breadth between zygomatic 511 513 ... 505 573 531 530 415 503 548 processes Breadth between temporal fossæ 270 309 325 300 349 317 311 242 302 313 Breadth of rostrum at base 319 331 345 324 380 337 320 249 307 337 Breadth of rostrum at middle 102 117 [b]94± 107 120 109 112 83 112 113 Breadth of premaxillæ at same 54 67 58 62 78 70 75 44 62 80 point Depth of rostrum at middle 66 81 80 79 118 117 113 50 77 107 Breadth of premaxillæ in 176 177 184 205 221 230 219 128 176 234 front of nares Greatest breadth of anterior 74 77 77 90 98 103 108 70 76 112 nares[c] Greatest length of temporal 161 158 154 149 152 140 146 133 143 155 fossa Greatest depth of temporal 81 73 77 79 87 74 89 67 80 76 fossa Length of orbit (ant.-post.) 131 133 132 130 137 126 117 113 134 132 Distance from anterior end of 78 92 82 70 83 89 85 61 82 99 orbit to maxillary notch Length of tympanic bulla ... ... ... ... 53 ... ... 54 ... 55 Breadth of tympanic bulla ... ... ... ... 24 ... ... 37? ... 25 Length of mandible ... 769 ... ... ... ... ... 679 ... 842 Length of symphysis ... 170 ... ... ... 184 ... 149 ... 176 Depth of mandible at coronoid ... 153 ... ... ... ... ... 133 ... 153

[a] About 150 mm. lacking from end of beak.
[b] A little abraded.
[c] Taken on a level with the curve of the inner margin of the
premaxillæ. Is only approximate.

SEX CHARACTERS.

It will be found from an examination of the foregoing descriptions that in those specimens in which the sex is known to be female, or is marked as such, the premaxillæ are comparatively narrow, the mesirostral ossification only slightly developed, the prenarial basin undeveloped, and the teeth quite slender, with a diameter of from 10 to 14 mm. As the teeth in some of them have closed roots there can be no doubt that they are adults. On the other hand, those skulls known or believed to be from adult males have the mesirostral ossification enormously developed, a deep prenarial basin, and fusiform teeth with closed roots and a diameter of from 25 to 30 mm. It appears to be a fact, therefore, that in the females the mesirostral ossification is never greatly developed at any age, that the teeth are never thick and fusiform, and that the prenarial region is never deeply concave. Immature individuals present, of course, the appearance of the females, except that the teeth are open at the root and that the mesirostral ossification is not developed at all. Conversely, the females, broadly speaking, always present characters of immaturity, but in adults the roots of the teeth are, of course, closed.

That these conclusions are correct is borne out by an examination of descriptions and figures of specimens from other parts of the world, for which purpose a few are available in the writings of New Zealand zoologists and others. Hector, for example, in 1873,[40] published a description and figures of a skull from the Chatham Islands which had a large mesirostral ossification, deep prenarial concavity, and large, thick teeth, having a diameter of 34 mm. This is the same combination of characters found in the Newport specimen, which is known to be a male, and the Bering Island skulls supposed to be those of males.[41]

In 1876,[42] Haast figured and described a female 26 feet long, and hence presumably adult, from Lyttleton Harbor, New Zealand, which had a small development only of the mesirostral ossification, a slight prenarial depression, and rather slender teeth with closed roots and a diameter of 19 mm. This combination of characters is found in the Barnegat skull, also known to be an adult female.

In the same paper Haast describes[43] and figures the skull of another female from Akaroa Harbor, New Zealand. This individual was larger than the last and was accompanied by a suckling calf. Hence, there can be no doubt that it was mature. The skull shows a moderate development of the mesirostral ossification, and slender cylindrical teeth with closed roots and a diameter of 16 mm.

It is demonstrated from the foregoing discussion, I think, that the sexes can be distinguished by the skulls, when adult, or by the teeth alone.

Reverting now to _Ziphius gervaisii_, which was mentioned on p. 30 as perhaps constituting a separate species, it will be seen by examining the figures given by Gervais[44] of the skull on which it was based that the latter presents the combination of characters peculiar to the female of _Z. cavirostris_. This skull, which was from Aresquiers (Hérault), France, was 888 mm. long, and hence, presumably, adult. The mesirostral ossification is but slightly developed, the prenarial concavity moderate, the teeth small, slender, and cylindrical, with closed roots and a diameter of 14 mm. There seems to be no sufficient reason for regarding this skull as representing a species distinct from _cavirostris_.

The specimen from Buenos Ayres described and figured by Burmeister in 1868[45] was an immature male. In the skull the mesirostral ossification was lacking, the premaxillæ were flat, and the teeth conical and acuminate, with open roots, and a diameter of 12 mm. This individual was 12 feet 11½ inches (3.95 m.) long, and hence about as long as the Charleston specimen, but the skull was apparently 680 mm. long, while that of the Charleston specimen is 797 mm. long. In the latter the teeth are 45 mm. long and 10 mm. in diameter, while the tooth figured by Burmeister is 31 mm. long and 12 mm. in diameter. From these data it appears improbable that the sex of immature individuals can be determined from the skull or teeth.

TEETH.

The teeth of the various North Atlantic and North Pacific specimens merit a somewhat more detailed description than is given on pages 50 to 53. Six pairs of teeth from six different individuals are available for comparison. Their dimensions are as follows:

_Dimensions of the teeth of Ziphius cavirostris._

Cat. Locality. Age. Sex. Teeth.
No.
Length. Greatest
diameter.
mm. mm.
21975 Charleston, South Carolina[a] Young Female 45 10
20971 Barnegat City, New Jersey Adult Female 56 13
22069 Bering Island Adult (Female?) 41 14
20993 do[b] Adult (Male?) 48 25
21248 do Adult (Male?) 58 30
49599 Newport, Rhode Island Adult Male 63 29

[a] Type of _Z. semijunctus_.
[b] Type of _Z. grebnitzkii_.

_21975. Charleston, South Carolina._—Young female. (Type of _Z. semijunctus_.) The teeth are slender, conical, and acuminate, largest at the base and tipped for about 2 mm. with white enamel. The remainder of the teeth is coated with a thin layer of cement. The teeth in what appears to be their natural position protrude horizontally from the mandible for about 17 mm. They are slightly curved upward near the tip and are oval, or elliptical, in section, the transverse diameter being a little less than the vertical diameter. They are a little flattened externally. The surface is smooth. They are open at the root, and hollow. (Pl. 38, figs. 1, 2; pl. 22, fig. 1.)

Doctor Manigault, curator of the Charleston Museum, wrote to Professor Cope regarding these teeth, as follows:

Another peculiarity of the head consists in the lower maxillary bones
being provided each at its point with a single small and very sharp
tooth. These were not noticed during the dissection, owing to their
being too much embedded in the integuments.[46]

_20971. Barnegat City, New Jersey._—Adult female. The teeth are slender, cylindrical, and irregularly pointed at both ends. The tips show what appears to be an inner core of dentine which has been worn down nearly to the cement coating and somewhat fractured. The cement coating is several millimeters thick, but does not increase the diameter of the teeth near the middle, so that they remain irregularly cylindrical throughout. The surface of the cement is rough and irregular. The root is short, conical, and closed at the end. These teeth are nearly straight. As they have been extracted from the jaw and the latter is broken it is not possible to distinguish which is the upper and which the lower surface, but they are irregularly oval in section, and a little compressed. (Pl. 38, figs. 3-5.)

In my original notes on this specimen, I recorded that there was a small pair of teeth behind the larger ones described above. Mention of these will be made again later. (See p. 57.)

_22069. Bering Island._—Adult female (?). The teeth are in position in this specimen and are nearly horizontal in position, but a little inclined upward and toward each other. They do not extend beyond the tip of the jaw nor up to the level of the upper surface of the symphysis, but protrude about 13 mm. beyond the alveoli on the side. They are rather slender, somewhat fusiform, blunt at both ends and slightly curved upward. The surface is irregular. They are nearly round in section. The root is closed, and the apex shows what appears to be a core of dentine surrounded by cement. There is a depression on the inner side near the root. These teeth are remarkable as intermediate in form between those of the preceding specimen and those of the specimens next to be mentioned. (Pl. 38, figs. 6, 7; pl. 22, fig. 3.)

_20993. Bering Island._—Adult male (?). (Type of _Z. grebnitzkii_.) These teeth are almond-shaped and very symmetrical. They are thickest near the base and taper gradually to the tip, which is quite acute. They are somewhat compressed and hence elliptical in section, the vertical diameter being greater than the transverse diameter. One side (probably the inner) is flattened. They are slightly curved upward toward the apex, which is a little worn and fractured. The root is very short and conical. It is nearly closed, but a very small canal extends upward for about 10 mm. The surface of the tooth is quite smooth, but dull in the lower half. The line of demarcation between cement and dentine is not evident. (Pl. 38, figs. 8, 9; pl. 23, fig. 1.)

_21248. Bering Island._—Adult male (?). In this specimen the teeth are still in the natural position in the jaw. They are held in place by ligaments and protrude far beyond the alveoli, only about one-ninth of their length being below the superior border. They incline forward at an angle of about 45° with the longitudinal axis of the jaw and diverge slightly at the tips.