Chapter I: Part 1

UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY

Volume 15, No. 6, pp. 251-295, 9 figs.

October 4, 1963

A Revision of Snakes of the Genus Conophis
(Family Colubridae, from Middle America)

BY
JOHN WELLMAN

UNIVERSITY OF KANSAS
LAWRENCE
1963

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Theodore H. Eaton, Jr.

Volume 15, No. 6, pp. 251-295, 9 figs.
Published October 4, 1963

UNIVERSITY OF KANSAS
Lawrence, Kansas

PRINTED BY
JEAN M. NEIBARGER. STATE PRINTER
TOPEKA. KANSAS
1963

29-5936

A Revision of Snakes of the Genus Conophis (Family Colubridae, from Middle America)

BY

JOHN WELLMAN

CONTENTS

PAGE

INTRODUCTION 253

ACKNOWLEDGMENTS 254

MATERIALS AND METHODS 254

GENUS Conophis Peters 255
Key to the Species and Subspecies 257
Analysis of Characters 257
Scutellation 258
Size and Proportions 258
Color Pattern 260
Sexual Dimorphism 260
_C. lineatus_ 262
_C. lineatus dunni_ 262
_C. lineatus lineatus_ 267
_C. lineatus concolor_ 270
_C. nevermanni_ 272
_C. pulcher_ 274
_C. vittatus_ 277
Skull 282
Dentition 288
Vertebrae 288
Hemipenes 289
Food and Feeding 289
Effect of Poison 290

TAXONOMIC RELATIONSHIPS AND EVOLUTION 291

SUMMARY 292

LITERATURE CITED 293

INTRODUCTION

Need for a comprehensive systematic review of the snakes of the genus _Conophis_ was pointed out by Stuart (1954a, b). Since these snakes appeared to be of zoogeographic importance in the Central American region, I undertook the review as set forth on the following pages.

ACKNOWLEDGMENTS

For permission to examine specimens, and for information concerning specimens in their care, I am grateful to Mr. L. C. Battersby and Miss Alice G. C. Grandison, British Museum (Natural History); Mr. Charles M. Bogert and Dr. Richard G. Zweifel, American Museum of Natural History; Dr. Doris M. Cochran, United States National Museum; Prof. William B. Davis, Agricultural and Mechanical College of Texas; Dr. Josef Eiselt, Naturhistorisches Museums, Vienna; Prof. Norman Hartweg and Prof. Laurence C. Stuart, Museum of Zoology, University of Michigan; Dr. Robert F. Inger, Chicago Natural History Museum; Dr. Alan E. Leviton, California Academy of Sciences; Mr. Edmond V. Malnate, Academy of Natural Sciences, Philadelphia; Prof. George S. Myers, Stanford University Natural History Museum; Mr. Wilfred T. Neill, Ross Allen's Reptile Institute; Mr. Neil D. Richmond, Carnegie Museum; Dr. William J. Riemer, University of Florida Collections; Prof. Robert C. Stebbins, Museum of Vertebrate Zoology, University of California; Prof. Hobart M. Smith, University of Illinois Natural History Museum; and Dr. Ernest E. Williams, Museum of Comparative Zoology, Harvard.

Prof. William E. Duellman supplied invaluable information and guidance in my study. I am grateful to Prof. E. Raymond Hall for use of facilities of the Museum of Natural History and editorial assistance. I thank Prof. Laurence C. Stuart and Prof. Edward H. Taylor for information and suggestions. My own field experience in Middle America came as a result of assisting Professor Duellman in his own researches supported by a grant from the National Science Foundation (NSF-G 9827). For these things I am deeply grateful. Specimens that I have seen alive were collected by field companions Dale L. Hoyt and Jerome B. Tulecke. Finally, I am grateful to my wife, Margaret L. Wellman, for much help including typing much of the manuscript.

MATERIALS AND METHODS

Of the 325 specimens of the genus _Conophis_ available to me, representing most of those in museum collections, scale counts were made in the usual manner on 309. Ventrals were counted following the system proposed by Dowling (1951:97-99); the anal plate was not included. The anteroposterior position of the place where reduction occurs in the number of the dorsal rows of scales is designated by citing the number of the ventral scale directly beneath that place.

Measurements were taken to the nearest millimeter by means of a millimeter stick. Body length is the distance from the tip of the snout to the posterior edge of the anal plate; tail length, from the latter point to the tip of the tail; and total length, the sum of the body plus tail.

Descriptions of color are based on preserved specimens. Where descriptions of the color of living individuals are given, the data were taken from Kodachrome slides made available to me by William E. Duellman. Due to the transient nature of the longitudinal dark stripes in these snakes, no standard terminology has been devised, except that the posterior continuations of the stripes which on the head pass through the eye are termed lateral stripes; the posterior continuations of the median stripe of the head are termed dorsolateral stripes. A paravertebral stripe is one that is present on the scale-row on either side of, but not including, the mid-dorsal (vertebral) scale-row.

In order to reduce confusion in the discussion of variation, the numbers designating the rows of dorsal scales are written as 1st, 2nd, whereas the numbers designating the stripes are written as first, second.

Except in three dried skeletons, teeth were counted on dentigerous bones _in situ_. Since teeth are often missing, the sockets were counted in order to obtain an accurate count.

In accounts of the species and subspecies, the observed range of variation is followed by the mean in parentheses; in some instances the mean is followed by the standard deviation, also in parentheses. An example is 65-79 (70.6 +- 3.93).

Each synonymy includes all generic and specific combinations known to me that have been used for the genus, and, in addition, references to catalogues, checklists, and reports of collections.

Localities of occurrence that are not plotted on the distribution maps are recorded in italic type under Specimens Examined. In the list of Specimens Examined the localities and specimens are listed in the following order: countries in alphabetical order; states or departments in alphabetical order in each country; localities in alphabetical order in each state or department; museum numbers in numerical order after the abbreviations of names of museums. When more than one specimen bears a single catalogue number, the number of specimens is given in parentheses following the museum catalogue number. Specimens for which data are given only as to country or to state or department are listed first after the name of that political unit under "no specific locality."

The abbreviations for the museum collections are:

AMNH American Museum of Natural History
ANSP Academy of Natural Sciences of Philadelphia
BMNH British Museum (Natural History)
CAS California Academy of Sciences
CNHM Chicago Natural History Museum
ERA-WTN E. Ross Allen-Wilfred T. Neill, Ross Allen's Reptile Institute
KU University of Kansas Museum of Natural History
MCZ Museum of Comparative Zoology, Harvard
MVZ Museum of Vertebrate Zoology, University of California
NMW Naturhistorisches Museums Wien, Vienna
SU Stanford University Natural History Museum
TCWC Texas Cooperative Wildlife Collection, Agricultural and
Mechanical College of Texas
UF University of Florida Collections
UIMNH University of Illinois Museum of Natural History
UMMZ University of Michigan Museum of Zoology
USNM United States National Museum

Family COLUBRIDAE

Subfamily Xenodontinae

Genus =Conophis= Peters

_Tomodon_ (part) Dumeril, Bibron and Dumeril, Erpetologie Generale,
7(pt.2):936, February 7(pt.2):936, February 25, 1854 (_lineatus_
and _vittatus_); Salvin, Proc. Zool. Soc. London, 28:455, 1860
(_pulcher_).

_Psammophis_ (part), Guenther, Catalogue of Colubrine Snakes in
the Collection of the British Museum, London, 1858:135
(_lineatus_).

_Conophis_ Peters, Monatsb. Akad. Wiss. Berlin, 1860:519-520,
pl., fig. 3 (_vittatus_); Cope, Proc. Acad. Nat. Sci.
Philadelphia, 13:300, December 28, 1861 (_lineatus concolor_);
Proc. Acad. Nat. Sci. Philadelphia, 18:318-319, February 20,
1867 (_lineatus concolor_); Proc. Acad. Nat. Sci.
Philadelphia, ser. 2, 8:137, 1876 (_pulcher_); Bocourt in
Dumeril, Bocourt and Mocquard, Mission Scientifique au Mexique
et dans l'Amerique Centrale, 2:643-644, pl. 38, fig. 5, 1886
(_lineatus lineatus_); Cope, Proc. Amer. Philos. Soc., 23:489,
October 28, 1886; Hoffmann, Klassen und Ordnungen des
Thier-Reichs. Reptilien. Bd. 6, 3:1707, 1890; Cope, Trans.
Amer. Philos. Soc., 18:207, April 15, 1895; Dunn, Bull.
Antivenin Inst. Amer., 2(1):21, 24, April, 1928; Copeia, no.
4:214, December 31, 1937 (_nevermanni_).

_Tachymenis_ (in part), Garman, Bull. Essex Inst., 16:33,
January 9, 1884 (_vittatus_ and _lineatus_).

_Erythrolamprus_ (in part), Ditmars, Bull. Antivenin Inst.
Amer., 2(2):27-29, June.

_Coniophanes_ (in part), Wettstein, Sitz. Akad. Wiss. Wien,
mathem-naturw. kl. 143:37-38, 1934 (_nevermanni_).

_Historical summary._--In 1854 Dumeril, Bibron and Dumeril described and figured _Tomodon lineatum_ from America. In 1860 Peters described and figured as a new genus and species, _Conophis vittatus_, based on a specimen that he had obtained from a dealer in Hamburg. The provenance of this specimen is not known, for it was discovered aboard a ship near the mouth of the Mississippi River. It was not until 1871 that Cope included _lineatus_ in the genus _Conophis_. Cope (1861) proposed the name _Conophis vittatus_ (_nec_ Peters, 1860). Later (1900) he changed its name to _Conophis lineaticeps_. Early uncertainty of the relationships of the species _lineatus_ caused Guenther (1858) to place it in the genus _Psammophis_. With the exception of Garman (1884a and 1884b) who placed _lineatus_ in the genus _Tachymenis_, and Wettstein (1934) who reported five specimens of _Conophis nevermanni_ as _Coniophanes i. imperialis_, all specimens reported after 1876 were placed in the genus _Conophis_.

The only previous attempt to review the systematics of this genus was made by Smith (1941) who based his study primarily on specimens in the United States National Museum. He examined only 28 specimens, including none of one species (_nevermanni_).

_Description._--Hemipenis slightly bifurcate having forked sulcus spermaticus, large spines near base, and smaller spines or papillae on flounces nearer apices; prediastemal maxillary teeth 8-12, subequal in length, and followed by short diastema and one enlarged fang or two; fangs grooved, only one functional at any one time, unless snake is in process of shedding teeth; teeth 6-10 on palatine, 15 to 19 on pterygoid, 15 to 21 on dentary; teeth on dentary decreasing in size posteriorly; large parotid (venom) gland on either side of head in temporal region; head shields of basically unmodified colubrid type excepting decurved rostral; rostral concave below and therein modified for burrowing; internasals and prefrontals paired; nasals divided; loreal single; preocular one, rarely two; postoculars, two; supralabials, 7-8, 3rd and 4th or 4th and 5th under eye; infralabials, 8-11, usually 9 or 10; temporals, normally 1 plus 2 plus 3; chin-shields subequal in length; ventrals, 149-183, rounded and overlapping; caudals, 55-89, paired and imbricate; anal divided; dorsal scales smooth and in 19 rows at mid-body with no apical pits or keels; scale reduction normally involving fusion of 3rd and 4th rows, resulting in 17 scale-rows near tail; tail length more than 20 per cent of body length; maximum total length exceeding 1.1 meters; dorsal color pattern consisting of dark stripes, or no darkening, on paler ground-color; ventral surfaces immaculate pale yellowish or white, except on specimens having single lateral dark spots on some or all ventrals; pupil round; diurnal or crepuscular; feeding primarily on small lizards, sometimes on small mammals or other snakes.

_Distribution._--Semi-arid regions of southern Mexico and Central America as far south as Costa Rica.

KEY TO THE SPECIES AND SUBSPECIES

Although many juveniles differ greatly in general coloration from the adults, both the juveniles and the adults of any species or subspecies can be identified from the following key; juveniles differ from adults in extent and intensity of dark pigmentation but not in rows of scales involved.

1. Seven supralabials (3rd and 4th below orbit); 3 to 8 dark
stripes along body 2

Eight supralabials (4th and 5th below orbit); unstriped or with
more than 4 dark stripes along body, or dark with 2 or 4 pale
stripes 3

2. Dark stripes involving no more than one longitudinal
scale-row _C. lineatus lineatus_ (part), p. 267

Dark stripes involving at least two adjacent scale-rows
_C. vittatus_, p. 277

3. Supralabials having black borders above; head and body
generally black with 2 or 4 white lines running length
of body _C. nevermanni_, p. 272

Supralabials immaculate or having dark borders below; head
and body usually pale with dark stripes, or without stripes 4

4. Lateral dark stripe through eye involving upper half of second
scale-row; dark stripe on paravertebral row, at least
posteriorly _C. pulcher_, p. 274

Lateral dark stripe becoming indistinct on body, or restricted
to 4th or 3rd and 4th rows anteriorly, not involving 2nd
scale-row on anterior 1/3 of body (an auxiliary lateral stripe
sometimes present involving 2nd row); no paravertebral stripes 5

5. Stripes disappearing posteriorly (except for small spots of
pigment on scale-row 4 or 7); 1st scale-row unpigmented
_C. lineatus concolor_, p. 270

Stripes present posteriorly; 1st scale-row pigmented 6

6. Lateral stripes narrow on nape, restricted to 4th scale-row
on body _C. lineatus lineatus_ (part), p. 267

Lateral stripes involving 3rd and 4th rows, at least on
nape _C. lineatus dunni_, p. 262

Analysis of Characters

Characters showing inter-specific and intra-specific variation and that have a wide range of variation were analyzed statistically, when possible, in order to determine extent of variation. One character (see table 3) was analyzed for sexual dimorphism, and for it the coefficient of difference is also given. The statistical terms and formulae have been adopted from Mayr, Linsley and Usinger (1953). Dorsal head shields varied individually and were of no taxonomic importance. Osteological and hemipeneal characters did not show enough variation to be considered here.

Scutellation

Labials, dorsals, ventrals, and subcaudals were the most useful scales.

_Labials._--All species usually have eight supralabials except _C. vittatus_, which has seven. The only other population having a relatively high frequency of occurrence of seven supralabials is _C. l. lineatus_. In specimens having eight supralabials, the fourth and fifth enter the orbit; in specimens having seven supralabials, the third and fourth enter the orbit (the second and third are fused). Usually there are ten infralabials, sometimes nine or eleven; specimens having seven supralabials usually have nine infralabials, sometimes eight, rarely ten.

_Dorsals._--Although there is no variation in the number of rows of dorsal scales, there is some in the method of scale reduction. There are 19 rows of dorsal scales from close behind the head to about midway on the body where two rows are lost, leaving 17 rows from there to near the base of the tail. This reduction is accomplished by fusion of the scales of the 3rd and 4th rows or sometimes by the dropping out of the 3rd row. The place at which reduction occurs in number of dorsal scales in relation to the ventral (scale) directly below is highly variable and of little taxonomic importance (table 1).

TABLE 1.--VARIATION IN THE PLACE OF DOSAL SCALE REDUCTION IN CONOPHIS.

Key to Columns ==================================== Std. Dev. = Standard Deviation Std. Err. = Standard Error Coe. Var. = Coefficient of Variation

==============+===========+========+=======+======+======+====== | Number of | | | Std. | Std. | Coe. Taxon | Specimens | Range | Mean | Dev. | Err. | Var. --------------+-----------+--------+-------+------+------+------ _l. concolor_ | 45 | 89-114 | 102.5 | 5.57 | 0.83 | 5.43 _l. dunni_ | 36 | 91-111 | 102.1 | 4.59 | 0.77 | 4.50 _l. lineatus_ | 26 | 91-107 | 100.2 | 3.59 | 0.72 | 3.58 _nevermanni_ | 6 | 84- 97 | 93.2 | 4.71 | 1.92 | 5.05 _pulcher_ | 26 | 94-119 | 104.6 | 4.90 | 0.96 | 4.68 _vittatus_ | 170 | 84-118 | 102.3 | 6.60 | 0.16 | 6.45 --------------+-----------+--------+-------+------+------+------

_Ventrals._--The number of ventral scutes varies from 149-183, and shows no significant variation in the means (table 2).

_Subcaudals._--The number of subcaudal scutes varies from 55 to 89. In some populations there is no overlap in the range of variation of males and females. The total variation and sexual dimorphism are analyzed in table 3.

Size and Proportions

Although considerable variation in size is observable, little taxonomic use is made of size since sufficient series are not available to determine age classes. The subspecies attaining the largest size is _C. lineatus concolor_; all others are smaller and of about the same size and proportions. The longest specimen, a male of _C. l. concolor_, has a body length of 893 mm., a tail length of 274 mm., and a total length of 1167 mm.

TABLE 2.--VARIATION IN THE NUMBER OF VENTRALS IN CONOPHIS.

Key to Columns ==================================== Std. Dev. = Standard Deviation Std. Err. = Standard Error Coe. Var. = Coefficient of Variation

==============+===========+=========+=======+======+======+====== | Number of | | | Std. | Std. | Coe. Taxon | Specimens | Range | Mean | Dev. | Err. | Var. --------------+-----------+---------+-------+------+------+------ _l. concolor_ | 45 | 158-170 | 163.7 | 1.56 | 0.23 | 0.95 _l. dunni_ | 36 | 159-178 | 167.2 | 4.56 | 0.76 | 2.72 _l. lineatus_ | 26 | 157-169 | 163.5 | 3.59 | 0.72 | 2.20 _nevermanni_ | 6 | 173-183 | 176.5 | 4.00 | 1.63 | 2.27 _pulcher_ | 26 | 149-180 | 169.5 | 5.31 | 1.04 | 3.13 _vittatus_ | 171 | 149-180 | 163.7 | 6.33 | 0.15 | 3.87 --------------+-----------+---------+-------+------+------+------

TABLE 3.--SEXUAL DIMORPHISM AS INDICATED BY VARIATION IN THE NUMBER OF
SUBCAUDALS IN CONOPHIS.

Key to Columns ==================================== Num. Spc. = Number of Specimens Std. Dev. = Standard Deviation Std. Err. = Standard Error Coe. Var. = Coefficient of Variation Coe. Dif. = Coefficient of Difference

====================+=====+====+=======+======+======+======+======+=====
| |Num.| | | Std. | Std. | Coe. | Coe.
Taxon | Sex |Spc.| Range | Mean | Dev. | Err. | Var. | Dif.
--------------------+-----+----+-------+------+------+------+------+-----
_lineatus concolor_ | [M] | 22 | 68-74 | 70.3 | 2.14 | 0.46 | 3.04 |
| | | | | | | | 1.97
| [F] | 16 | 56-65 | 61.8 | 2.18 | 0.55 | 3.53 |
| | | | | | | |
_lineatus dunni_ | [M] | 14 | 67-80 | 74.5 | 3.86 | 1.03 | 5.18 |
| | | | | | | | 0.95
| [F] | 16 | 60-72 | 67.1 | 3.91 | 0.97 | 5.82 |
| | | | | | | |
_lineatus lineatus_ | [M] | 11 | 67-73 | 69.8 | 6.17 | 1.85 | 8.84 |
| | | | | | | | 0.60
| [F] | 9 | 60-66 | 62.4 | 6.17 | 2.06 | 9.89 |
| | | | | | | |
_nevermanni_ | [M] | 3 | 82-89 | 85.3 | .... | .... | .... |
| | | | | | | | ....
| [F] | 2 | 71-76 | 73.5 | .... | .... | .... |
| | | | | | | |
_pulcher_ | [M] | 7 | 70-79 | 74.3 | 3.11 | 1.17 | 4.19 |
| | | | | | | | 0.93
| [F] | 11 | 65-71 | 68.2 | 3.42 | 1.08 | 5.01 |
| | | | | | | |
_vittatus_ | [M] | 95 | 59-76 | 67.8 | 3.33 | 0.34 | 4.91 |
| | | | | | | | 1.28
| [F] | 58 | 55-66 | 60.0 | 2.75 | 0.36 | 4.58 |
--------------------+-----+----+-------+------+------+------+------+-----

Color Pattern

This is the primary feature used to separate species and subspecies in this genus. The color pattern consists of three black or deep brown stripes on the dorsal part of the head, one mid-dorsally, and one on each side of the head passing through the eye. On the body, there are usually dark longitudinal stripes on a pale tan or white background. There may be as few as three in _vittatus_, and as many as 13 in _l. dunni_; except that there is none in _C. l. concolor_. There are two pairs of primary dark stripes. The first is the body stripe that is the posterior extension of the stripe which on the head passes through the eye and is termed the lateral stripe. The other primary stripe is the posterior continuation of the mid-dorsal head stripe. Usually it is split into two dorsolateral stripes on the body. Stripes may be present on the scale-row to either side of the primary stripe. These stripes are usually dark brown or black and are the secondary stripes. Finally, additional stripes may be present that are paler brown and bear no direct relationship to the primary stripes. These are auxiliary stripes.

Every stripe originates either as broad continuous stripe or as a row of spots or dashes, forming a discontinuous stripe, which in some specimens becomes continuous posteriorly. The stripes are usually black or deep brown, although auxiliary stripes are sometimes paler. The dorsal ground color is pale brown, tan, olive, or white; usually the ground color is palest ventrally and darkest dorsally.

In some specimens of _Conophis_ the lateral tips of the ventrals are spotted, one spot on each end of each ventral. Otherwise, the ventrals are immaculate white.

In some species there is considerable ontogenetic change in color pattern, although the juveniles bear the basic color characteristics of the adults. For example, juveniles of the sympatric species _C. lineatus dunni_ and _C. pulcher_ can be separated on the basis of which scale-rows are darkly pigmented. _C. l. dunni_ has eight stripes in juveniles and as many as 13 in adults. Juveniles show a greater contrast between the black stripes and the pale ground color than do adults. With increased age (size) the stripes in some populations become paler and are split; simultaneously the ground color becomes darker.

Sexual Dimorphism

Sexual dimorphism is evident in all species and subspecies of _Conophis_. Differences always exist in the number of subcaudals and in the tail/body ratio; males have more subcaudals and relatively longer tails than do females (table 3). Otherwise, there is little sexual dimorphism in these snakes. Males and females cannot be differentiated by any feature of coloration.

Formulation of a biological concept of the species as defined by Mayr (1942) is difficult when most of the data primarily relied upon are from preserved specimens. Nevertheless, a total view of variation was attempted so that differences within and between populations could be recognized. Differences, between populations, that seem to be part of a continuous or internal cline (Huxley, 1942) are not used for characterizing subspecies.

=Conophis lineatus= (Dumeril, Bibron and Dumeril)

_Tomodon lineatum_ (in part) Dumeril, Bibron and Dumeril,
Erpetologie Generale, 7(pt. 2):936-938, February 25, 1854.

_Diagnosis._--No dark pigmentation posterior to nape; lateral dark stripe anteriorly passing through eye and posteriorly involving 4th or 3rd and 4th scale-rows only; first scale-row darkly pigmented; no paravertebral dark stripe; six to thirteen (or no) dark stripes at mid-body; usually eight (sometimes seven) supralabials immaculate white or having dark ventral margins.

_Variation._--The variation in this species is discussed more completely in the descriptions of the subspecies. One hundred and seven specimens have 157 to 178 (164.8) ventrals. Eighty-eight of these snakes having complete tails have 56 to 80 (68.0) subcaudals; the number of ventrals plus subcaudals varies from 222 to 247 (233.5) in 87 of these. On 107 specimens the reduction from 19 to 17 dorsal scale-rows takes place between ventrals 89 and 114 (101.8). Sexual dimorphism is evident in the number of subcaudals; there are, on the average, fewer subcaudals in females than in males of each subspecies. The largest specimen is a male _C. l. concolor_ (USNM 46345) from Chichen Itza, Yucatan, Mexico, having a body length of 893 mm., a tail length of 274 mm. and a total length of 1167 mm. The smallest is a juvenile _C. l. dunni_ (MCZ 49749) from Tegucigalpa, Honduras, having a body length of 162 mm., a tail length of 51 mm. and a total length of 213 mm.

The greatest variation is in coloration. Dark color, or lack thereof, has been used to separate the subspecies of _C. lineatus_. The ground-color is pale brown, pale olive or white, either with no stripes on the body or with eight to thirteen dark stripes at mid-body. Specimens having dark stripes on the body always have black or dark brown pigmentation on the first, 4th and 7th dorsal scale-rows. In some there is dark pigmentation on the 2nd, 3rd, 8th and 10th rows of scales. The stripes appear on the nape or farther posteriorly, usually on the anterior third of the body, either as a series of spots or dashes that form a continuous stripe farther posteriorly or as a continuous stripe.

The ventrals usually have more or less conspicuous dark spots laterally on those specimens having dark stripes present on the dorsum; spots are absent on all specimens having no dorsal stripes and on some specimens having dorsal stripes. Except for the dark lateral spots (when present) the ventrals are immaculate white. Usually the dorsal ground-color is pale tan, especially on the striped forms. The ground-color is usually palest on the lower dorsal scale rows and darkest dorsally.

Three populations are separable as subspecies; one has no stripes on the body and occurs in the Yucatan Peninsula. The other two have stripes on the dorsum and vary clinally in coloration from the north (Veracruz, Mexico) to south (Costa Rica) (Fig. 2). Reasons for separating these widespread, variable snakes into two subspecies are that they are discontinuous in distribution (the population in Veracruz is disjunct from the one that extends from Guatemala to Costa Rica), and that these populations have distinctly different color patterns.

=Conophis lineatus dunni= Smith

_Psammophis lineatus_, Guenther, Catalogue of Colubrine Snakes
in the Collection of the British Museum, p. 135, 1858.

_Conophis lineatus_, Cope, 3rd Ann. Rept. Peabody Acad. Sci.,
p. 82, 1871; Proc. Acad. Nat. Sci. Philadelphia, 23:204,
October 24, 1871; Journ. Acad. Nat. Sci. Philadelphia, ser. 2,
8:137, 1876; Bull. U. S. Natl. Mus., 32:77, 1887; Guenther,
Biologia Centrali-Americana, p. 165, March, 1895; Boulenger,
Catalogue of the Snakes in the British Museum (Natural
History), 3:122-123, 1896; Werner, Arch. Naturges., 90, abt. A,
12:143, 1925; Schmidt, Zool. Ser. Field Mus. Nat. Hist.,
12:199-200, November 21, 1928; Amaral, Mem. Inst. Butantan,
4:212, 1929; Werner, Zool. Jahrb., 57:184, 1929; Stuart, Occas.
Papers Mus. Zool. Univ. Michigan, 292:5, June 29, 1934; Dunn,
Copeia, no. 4:214, December 31, 1937.

_Conophis lineatus similis_ Smith, Journ. Washington Acad.
Sci., 31:123-124, March 15, 1941 (Type.--United States National
Museum, No. 79963; type locality.--Managua, Nicaragua; _nec_
Bocourt _in_ Dumeril, Bibron and Mocquard, Mission Scientifique
au Mexique et dans l'Amerique Centrale, 2:647-648, 1886);
Cochran, Bull. U. S. Natl. Mus., 220:167, 1961.

_Conophis lineatus dunni_ Smith, Proc. U. S. Natl. Mus.
92:394-395, November 5, 1942; Savage, Trans. Kansas Acad. Sci.,
50:483-486, December 31, 1949; Taylor, Univ. Kansas Sci. Bull.,
34(pt. 1):145, October 1, 1951; Neill and Allen, Publ. Res.
Div. Ross Allen's Rept. Inst., 2:56, November 10, 1959;
Herpetologica, 16:146-148, fig. 2, September 23, 1960.

_Conophis pulcher pulcher_, Stuart, Misc. Publ. Mus. Zool.
Univ. Michigan, 69:79, June 12, 1948; Contr. Lab. Vert. Biol.
Univ. Michigan, 45:24, May, 1950; Contr. Lab. Vert. Biol.
Univ. Michigan, 49:14, August, 1951; Contr. Lab. Vert. Biol.
Univ. Michigan, 65:19-20 (part), March, 1954.

_Conophis pulcher plagosus_, Mertens, Zool. Anz., 148:93,
February, 1952; Abhand. Senken. Naturw. Gesell., 487:61-62,
December 1, 1952.

_Conophis lineatus nevermanni_, Taylor, Univ. Kansas Sci.
Bull., 37(pt. 1):563-565, fig. 16, October 15, 1955.

_Type._--United States National Museum, no. 79963, obtained by Lt. H. C. Kellers. Type locality: Managua, Nicaragua. There are also three paratypes; one a topotype (USNM 79964), one from "Nicaragua" (USNM 25237), and one from Esparta, Costa Rica (USNM 37758).

_Diagnosis._--Lateral dark stripe anteriorly passing through eye and posteriorly involving 3rd and 4th scale-rows; 1st scale-row darkly pigmented; no paravertebral dark stripe, although vertebral row sometimes darkly pigmented; six to thirteen stripes at mid-body; eight supralabials immaculate or having dark ventral margins.

_Variation._--Thirty-six specimens have 159 to 178 (167.2 +- 4.56) ventrals. Thirty of these snakes having complete tails have 60 to 80 (70.5 +- 5.36) subcaudals; the number of ventrals plus subcaudals varies from 224 to 247 (237.6). In 36 specimens the reduction from 19 to 17 dorsal scales takes place between ventrals 91 and 111 (102.1 +- 4.59). Sexual dimorphism is evident in the number of subcaudals; 16 females have 60 to 72 (67.1), and 14 males have 67 to 80 (74.5) subcaudals. The largest specimen (ERA-WTN BH-300) is a female from Augustine, British Honduras, having a body length of 732 mm., a tail length of 183 mm. and a total length of 915 mm. A juvenile (MCZ 49794) from Tegucigalpa, Honduras, has a body length of 162 mm., a tail length of 51 mm. and a total length of 213 mm.

The greatest variation is in coloration. The ground-color is pale brown or white with dark stripes of black or deep brown present dorsally and laterally. Some specimens from Costa Rica have as many as 13 dark stripes at mid-body (fig. 1, C). In these snakes the first row of dorsal scales bears a series of large, slightly elongated, dark spots; on the 2nd row a narrow dark brown stripe on the middle of the scales; on the 3rd a black stripe on the dorsal one-third to one-half of the scales; on the 4th and the 7th rows black stripes on the medial half of the scales of each row; on the 8th and 10th (vertebral) rows dark brown stripes on the medial third of the scales of each row. A specimen from Guatemala (UMMZ 107339) shows the greatest reduction of stripes and dark pigmentation (fig. 1, A); it has only eight stripes at mid-body: on the first row of dorsal scales a discontinuous stripe is formed by a series of dashes; the 3rd row bears a series of small black spots near the base and tip of each scale; the 4th and 7th rows bear continuous black stripes on the medial third to fourth of the scales of each row; the 8th row has extremely small dark spots near the tips of some scales.

The primary stripes, characteristic of the species _lineatus_, are those on the 1st, 4th and 7th rows of dorsal scales; these are the most prominent stripes. In some specimens these primary stripes begin as spots or dashes on the nape and become continuous stripes posteriorly; in others they are continuous for the length of the body. The stripe on the 1st row is most variable; usually it consists of only a discontinuous series of dashes for most of its length. The secondary stripes are those on the 3rd and 8th rows; of these, only the one on the 3rd scale-row is present on the nape. The stripe on the 3rd row in combination with the dark stripe on the 4th row is the posterior continuation of the dark stripe that on the head passes through the eye; this stripe is characteristic of _C. lineatus dunni_. Both secondary stripes usually begin anteriorly as a series of spots or dashes and become continuous stripes posteriorly; occasionally near the base of the tail they fuse with the primary stripes on the 4th and 7th rows. In some specimens in Costa Rica indistinct stripes are present on the 10th (posteriorly the 9th) rows, and in some specimens in Honduras, Nicaragua, and Costa Rica similar indistinct stripes are present on the 2nd row.

Usually there are more or less conspicuous dark spots laterally on the ventrals, but in some specimens there are no spots. Except for the dark lateral spots (when present) the ventrals are immaculate white. The dorsal ground-color is a pale brown or brownish white in preserved specimens on the 1st, 2nd, 3rd and 4th rows of scales where dark stripes or spots are not present. The ground-color of the dorsum between the 5th rows on each side is a somewhat darker shade of pale to medium brown.

Never is more than the lower one-third of each of the supralabials brown. In many specimens little or no brown is present on the lower margins of these scales. Some of the specimens having brown on the supralabials also have dusky markings of tan or gray on the chin and infralabials. Specimens from the northern part of the range (Guatemala) less frequently have dark chins and supralabials than do specimens from the southern part of the range (Costa Rica). There is, nevertheless, at any one locality considerable variation in the amount of dark pigmentation present on the chin and supralabials, thereby indicating that the slight geographic trend in this character is not significant.

Probably the most common pattern of dorsal coloration consists of eight or ten dark stripes (fig. 1, B). In snakes having this pattern the stripes on the 1st, 3rd, 4th and 7th rows are always present and prominent, although those on the 1st and 3rd rows sometimes are present as discontinuous rows of dashes. The ground-color from the venter to the 7th row is usually pale brown, and that dorsally between the 7th rows on each side is usually a darker, medium brown. A series of spots or dashes or a continuous stripe is sometimes present on the 8th row of scales.

Snakes having a larger number of dark stripes and more dark pigmentation occur in the southern part of the range. There seems to be a cline from paler snakes having fewer stripes in the north to darker snakes in the south.

In juveniles, there are six or eight black stripes boldly contrasting with a white or pale tan ground-color (fig. 3, A). The first pair of stripes is on the 1st scale-row; the second pair, on the 3rd and 4th scale-rows; the third pair, on the 7th row; the fourth pair (when present), on the 8th row. Ontogenetic change in coloration consists of the splitting of the second pair of dark stripes in the juvenile. Additional stripes may form later on the 2nd and/or 10th rows of dorsal scales.

_Remarks._--Savage (1949:483-486) stated that his specimen of _C. l. dunni_ (from Honduras) resembled _l. lineatus_ in having secondary stripes on the 2nd and 8th rows and dark pigmentation throughout the length of the 2nd row. As can be seen from the preceding discussion of variation, a specimen having this color pattern is clearly within the observed range of variation of _l. dunni_. The specimen in no way represents an intergrade between _C. l. dunni_ and _l. lineatus_.

A specimen in the British Museum (Natural History), catalogued in 1853 (no. 53.2.4.16), has the locality listed as "Mexico." Since this specimen is of _C. l. dunni_ and this subspecies occurs only south of Mexico, the locality must be considered erroneous; possibly the locality as recorded referred only to the fact that the specimen came from tropical Middle America.

The absence of paravertebral stripes, the presence of a lateral dark stripe on the nape involving the 3rd and 4th rows of scales, and the darkly pigmented 1st scale-row, in combination with the characteristics of the genus, distinguish _C. l. dunni_ from all other snakes in Mexico and Central America. The only sympatric species of this genus, _C. pulcher_, differs in that it has paravertebral stripes (though never a vertebral dark stripe). _Conophis pulcher_ has a lateral dark stripe that includes the upper half of the second scale-row on the anterior part of the body; stripes of _C. l. dunni_ never include more than the 3rd and 4th rows. Even as juveniles the paravertebral row is not darkly pigmented in _C. l. dunni_ as it is in _C. pulcher_.

_Distribution._--Semi-arid habitats from sea level to elevations of 1000 m. from the Cuilco Valley in western Guatemala, El Peten and British Honduras southeastward to northeastern and southern Honduras, western Nicaragua and northwestern Costa Rica (fig. 2).

_Specimens examined._--Total of 41 specimens, as follows: BRITISH HONDURAS: _Cayo District_: Augustine, ERA-WTN BH-300; _Mountain Pine Ridge, 10 mi. E Augustine_, ERA-WTN BH-298.

COSTA RICA: _no specific locality_, AMNH 17309. "_Cartago_," BMNH 71.11.22.15. _Puntarenas_: 32 km. N Barranca, KU 35630; Esparta, USNM 37758. "_San Jose_," ANSP 3480, 12232.

EL SALVADOR: _Morazan_: El Divisadero, CNHM 10999. _San Miguel: San Pedro_, MCZ 57061.

GUATEMALA: _El Peten_: Sojio (Toocog), AMNH 69969, 69986. _Huehuetenango_: flood plain Rio Cuilco, W of Finca Canibal, 18 km. N Tacana, UMMZ 98283. _Santa Rosa_: Santa Rosa, UMMZ 107339.

HONDURAS: _no specific locality_, AMNH 32814, UF 7657. _Cortes: Cofradia_, SU 8422; _Gracias_, CNHM 28560; _Hacienda de Santa Ana, W San Pedro Sula_, CNHM 5297; San Pedro Sula, UMMZ 68695(2); _near San Pedro Sula_, MCZ 27563. _Francisco Morazan: Potrero de Melio, Escuela Agricola Pan-americana_, MCZ 49987; Tegucigalpa, MCZ 49784, 49786, 49789-90, 49792, 49794.

MEXICO: _no specific locality_, BMNH 53.2.4.16.

NICARAGUA: _no specific locality_, UMMZ 65633, USNM 25237. _Leon_: El Polvon, MCZ 5645, 5696. _Managua_: Managua, USNM 79963-64; _3 mi. SW Managua_, KU 42315; _8 mi. WNW Managua_, KU 42314; _1 mi. N Sabana Grande_, KU 42311-13. _Matagalpa_: 1.5 mi. N Matagalpa, UMMZ 116537.

=Conophis lineatus lineatus= (Dumeril, Bibron and Dumeril)

_Tomodon lineatum_ (in part) Dumeril, Bibron and Dumeril,
Erpetologie Generale, 7(pt. 2):936-938, atlas, pl. 73,
February 25, 1854; Bocourt, Journ. de Zool., 5:406-407, 1876.

_Tomodon lineatus_, Jan, Arch. Zool. Anat. Fis., Genoa,
2(2):234, March 1863; Elenco sistematico degli ofidi. Milano,
p. 57, 1863; Muller, Reisen in den Vereinigten Staaten,
Canada, und Mexico. Bd. 3. Beitrage zur Geschichte, Statistik,
und Zoologie von Mexiko. 3:607, 1865; Jan and Sordelli,
Iconographie Generale des Ophidiens, Milano. liv. 19, pl. 6,
fig. 3, December, 1866; liv. 50, pl. 2, fig. 34, November,
1881.

_Tachymenis lineata_ (in part), Garman, Bull. Essex Inst., 16:
33, January 9, 1884; Mem. Mus. Comp. Zool., 8:60-61, July,
1884.

_Conophis lineatus_, Bocourt _in_ Dumeril, Bocourt and
Mocquard, Mission Scientifique au Mexique et dans l'Amerique
Centrale, 2:643-644, pl. 38, fig. 5, 1886; Cope, Trans. Amer.
Philos. Soc., 18:218, pl. 28, fig. 2, (hemipenis), April 15,
1895; Boulenger, Catalogue of the Snakes in the British Museum
(Natural History), 3:122-123 (part), 1896; Cope, Ann. Rept. U.
S. Natl. Mus. for 1898, pp. 1094-1095, 1242, pl. 26, fig. 2,
(hemipenis), 1900; Amaral, Mem. Inst. Butantan, 4:212, 1929;
Mittleman, Copeia, no. 2:122, June 30, 1944.

_Conophis lineatus lineatus_, Smith, Journ. Washington Acad.
Sci., 31:122, March 15, 1941; Proc. U. S. Natl. Mus., 92:395,
November 5, 1942; Proc. U. S. Natl. Mus., 93:407, October 29,
1943; Smith and Taylor, Bull. U. S. Natl. Mus., 187:43,
October 5, 1945; Shannon and Smith, Trans. Kansas Acad. Sci.,
52:505, December 31, 1949; Smith and Taylor, Univ. Kansas Sci.
Bull., 33(pt. 2):351, March 20, 1950; Werler and Smith, Texas
Journ. Sci. 4(4):565, December 30, 1952; Fugler and Dixon,
Herpetologica, 14:186, December 1, 1958.

_Type._--Museum National d'Histoire Naturelle, Paris, no. 3738. Type locality.--"Mexico," restricted to Veracruz, Veracruz, Mexico, by Smith and Taylor (1950:351). Little is known about the type specimen, and nothing, concerning its collector or the locality at which it was collected. Smith (1941:122) assumed that the specimen illustrated by Bocourt in Dumeril, Bocourt, and Mocquard (1886:pl. 38, fig. 5) was the type of _C. l. lineatus_. I have also made this assumption concerning the identity of the type specimen of this species, especially because of the many inconsistencies appearing in the plate accompanying the description by Dumeril, Bibron and Dumeril (1854:pl. 73), and by Jan and Sordelli (1866:pl. 6). Neither show the nape nor a regular number of dorsal scales by which accurate determination of color pattern can be made and by means of which _C. l. dunni_ and _C. l. lineatus_ can be separated.

_Diagnosis._--Lateral dark stripe anteriorly passing through eye and posteriorly involving fourth scale-row only; first scale-row darkly pigmented; no paravertebral stripe; no dark pigment on vertebral row; six or eight dark stripes at mid-body, secondary stripes often present posteriorly; usually eight (sometimes seven) supralabials immaculate or having dark ventral margins.

_Variation._--Twenty-six specimens have 157 to 169 (163.5 +- 3.59) ventrals. Twenty of these snakes having complete tails have 60 to 73 (66.5 +- 4.26) subcaudals; the number of ventrals plus subcaudals varies from 224 to 238 (230.1) in nineteen of these. In 26 specimens the reduction from 19 to 17 dorsal scale-rows takes place between ventrals 91 and 107 (100.2 +- 3.59). Sexual dimorphism is evident in the number of subcaudals; nine females have 60 to 66 (62.4), and 11 males have 68 to 73 (69.8) subcaudals. The largest specimen (AMNH 19643) is a male from "Mexico," having a body length of 626 mm., a tail length of 168 mm. and a total length of 786 mm. No small juveniles have been examined; the smallest specimen (AMNH 19618) is a male from Veracruz, Mexico, having a body length of 325 mm., a tail length of 90 mm. and a total length of 415 mm.

The greatest variation is in coloration. In preserved specimens the ground-color is white, tannish-white, or often pale blue, with dark stripes of black or deep brown present dorsolaterally and laterally. Secondary stripes of paler brown are sometimes present, but the pale browns have faded badly on many specimens. Normally four black stripes are present at mid-body--a lateral pair on the 4th row of dorsal scales and a dorsolateral pair on the 7th row (fig. 1, D). The lateral pair is the posterior continuation of the stripe that on the head passes through the eye; it continues on the nape as a narrow stripe on the 4th row only. In a few specimens the lateral stripe broadens to include the upper third of the 3rd row posterior to the nape. In some specimens both the dorsolateral and lateral dark stripes are present on the nape as a row of elongated spots or dashes that become continuous stripes of even width one-third to one-half of the distance posteriorly along the body; in other specimens the stripes are continuous on the nape. Posterior to the place of dorsal scale-reduction from 19 to 17 rows by the fusion of the 3rd and 4th rows, the lateral and dorsolateral stripes are moved downward by one row. In some specimens secondary black or dark brown stripes are present in the form of a series of dashes on the 5th and 8th rows; posterior to the place of scale reduction, these dashes are on the 4th and 7th rows. These dashes form a continuous stripe near the base of the tail. On the tail the secondary and primary stripes on adjacent rows sometimes fuse into a single broader stripe.

Usually the 1st row of dorsal scales is dark brown; in some specimens the brown on the 1st or 7th row has faded in preservative. A few specimens have small black spots on the moderate brown background of the 1st row; in others the 1st row is only a somewhat darker brown than the ground-color. The 2nd row sometimes is a medium brown, and appears to be an additional stripe.

The ventrals usually have more or less conspicuous dark spots laterally; in some specimens there are no spots. Except for the lateral spots (when present) the ventrals are immaculate white. The dorsal ground-color is pale brownish-white, white or pale blue between the 4th and 7th rows of dorsal scales and dorsally between the 7th rows on each side. Stripes are never present on the uniformly pale colored 8th, 9th and vertebral scale-rows.

Usually there are eight supralabials on each side; however, seven of the 27 specimens examined have seven supralabials on each side, and three others have seven on one side, and eight on the other. Never is more than the lower third of the supralabials dark brown. In many specimens little or no brown is on the supralabials. There is little or no brown on the chin.

Variation in coloration and in number of supralabials appears to be of no geographic significance.

Although no juveniles have been collected, I expect that juveniles resemble adults in coloration. Probably there would be a greater contrast between the dark stripes and the pale ground-color in juveniles.

In life an adult from three miles northwest of Lerdo de Tejada, Veracruz, Mexico (UMMZ 114484), had black stripes on the 4th and 7th rows of dorsal scales, and black spots on a brown background on the 1st row. The 2nd row had a medial, pale to medium brown auxiliary stripe on a brownish-white background. Posterior to the nape the 3rd row was medium brown. The area between the 4th and 7th rows and the dorsum between the 7th row of scales on each side was a pale brownish-white. Posterior to the place of scale-reduction the primary stripes were displaced downward by one row to the 3rd and 6th rows and secondary stripes originated as elongated spots on the 4th and 7th rows. Near the tail the secondary stripes were broad and continuous. The head was white or tannish-white with three dark brown or black stripes.

_Remarks._--In his diagnosis of _C. l. lineatus_, Smith (1941:122) states: "lateral dark stripe ... very narrow posterior to nape, extending along fourth scale row; posteriorly a stripe along third and eighth (farther posteriorly the seventh) scale rows; a narrow dark stripe along sixth scale row, continuous throughout length of body...." I fail to find a dark stripe on the 6th row throughout the length of the body. In all specimens that I have seen, there is a dark stripe on the 7th row anteriorly and on the 6th row posteriorly. In many specimens the stripes on the 3rd and 8th (posteriorly the 7th) scale-rows are absent or present so far posteriorly that the 8th row is never involved.

The dark brown on the first scale-row and the presence of a lateral dark stripe on the 4th row of dorsal scales only, in combination with the characteristics of the genus, distinguish _C. l. lineatus_ from all other snakes in Mexico.

_Distribution._--Semi-arid habitats on the coastal plain of Veracruz, Mexico, from Tecolutla to Lerdo de Tejada and Piedras Negras (fig. 2).

_Specimens examined._--Total of 27, as follows: MEXICO: _no specific locality_, AMNH 19614-15, 19621-24, 19642-43, NMW 16827. _Veracruz: no specific locality_, AMNH 19618-20, CAS 73640, NMW 16829; _4 km. S Alvarado_, KU 58124; _14 mi. N Alvarado_, UIMNH 46978; 6 mi. SE Boca del Rio, UIMNH 28023; Etiopa, 2 mi. S Tecolutla, UIMNH 3847; _ca._ 30 mi. E Jalapa, AMNH 81948; 3 mi. NW Lerdo de Tejada, UMMZ 114484-85; Paso del Macho, USNM 109708; Rio Blanco, 20 km. WNW Piedras Negras, KU 23253; Veracruz, AMNH 19612, UF 8990; _W side Veracruz_, AMNH 19616; _2 mi. W Veracruz_, AMNH 19617, 19619.

=Conophis lineatus concolor= Cope

_Conophis vittatus_ Cope, Proc. Acad. Nat. Sci. Philadelphia,
13:300, December 28, 1861 (_nec_ Peters, 1860; type.--United
States National Museum, no. 4941; type locality--"Peten,"
Guatemala); Journ. Acad. Nat. Sci. Philadelphia, ser. 2,
8:137, 1876; Bull. U. S. Natl. Mus., 32:76, 1887.

_Conophis concolor_ Cope, Proc. Acad. Nat. Sci. Philadelphia,
18:318-319, February 20, 1867; Journ. Acad. Nat. Sci.
Philadelphia, ser. 2, 8:137, 1876; Bocourt _in_ Dumeril,
Bocourt and Mocquard, Mission Scientifique au Mexique et dans
l'Amerique Centrale, 2:648, 1886; Mueller, Verh. Ges. Basel,
8:263, 1887; Cope, Bull. U. S. Natl. Mus., 32:77; 1887; Ann.
Rept. U. S. Natl. Mus. for 1898, p. 1095, 1900; Schmidt and
Andrews, Zool. Ser. Field Mus. Nat. Hist., 20:178, October 31,
1936; Andrews, Zool. Ser. Field Mus. Nat. Hist., 20:358,
December 28, 1937; Smith, Occas. Papers Mus. Zool. Univ.
Michigan, 388:7, October 31, 1938; Taylor and Smith, Univ.
Kansas Sci. Bull., 25:253, July 10, 1939; Smith, Zool. Ser.
Field Mus. Nat. Hist., 24:31, January 30, 1939; Cochran, Bull.
U. S. Nat. Mus., 220:167, 1961; Neill and Allen,
Herpetologica, 17:44-46, fig. 3, April 15, 1961.

_Conophis lineatus_ (in part), Guenther, Biologica
Centrali-Americana, p. 165, March, 1895; Gaige _in_ Pearse,
_et al._ Carnegie Inst. Washington Publ., 457:302, February 5,
1936.

_Conophis lineaticeps_ Cope, Ann. Rept. U. S. Natl. Mus. for
1898, pp. 1094-95, 1900 (Substitute name for _Conophis
vittatus_ Cope, 1861, _nec_ Peters, 1860).

_Conophis lineatus concolor_, Smith, Journ. Washington Acad.
Sci., 31:122-123, March 15, 1941; Proc. U. S. Natl. Mus.,
92:395, November 5, 1942; Proc. U. S. Natl. Mus., 93:407,
October 29, 1943; Smith and Taylor, Bull. U. S. Natl. Mus.,
187:43, October 5, 1945; Univ. Kansas Sci. Bull., 33(pt.
2):352, March 20, 1950.

_Types._--Two in the United States National Museum, no. 12368 (two specimens). Type locality: "Yucatan," restricted to Chichen Itza, Yucatan, Mexico by Smith and Taylor (1950:352).

_Diagnosis._--Dark stripes either absent posterior to the nape, or present as a row of small spots on fourth or seventh scale-row; no dark stripe on first scale-row; eight supralabials having dark ventral margins.

_Variation._--Forty-five specimens have 158 to 170 (163.7 +- 1.56) ventrals. Thirty-eight of these snakes having complete tails have 56 to 74 (66.7 +- 4.77) subcaudals; the number of ventrals plus subcaudals varies from 222 to 245 (230.6). In 45 specimens the reduction from 19 to 17 dorsal scales takes place between ventrals 89 and 114 (102.5 +- 5.57). Sexual dimorphism is evident in the number of subcaudals; 16 females have 56 to 65 (61.8), and 22 males have 68 to 74 (70.3) subcaudals. The longest specimen (USNM 46395) is a male from Chichen Itza, Yucatan, having a body length of 893 mm., a tail length of 274 mm., and a total length of 1167 mm. A juvenile (AMNH 38833) from Chichen Itza, Yucatan, has a body length of 194 mm., a tail length of 50 mm., and a total length of 244 mm.

The venter is immaculate white or pale yellow and the dorsum of the body is immaculate pale gray to pale olive. Some specimens have small dark brown spots on the tips of the scales of the 4th or of the 7th row, but never on both. Only on the nape are spots present on both the 4th and the 7th rows; these spots are the posterior continuations of the dark stripes on the head and on many specimens do not reach the nape. Posterior to the place of scale reduction from 19 to 17 rows by the fusion of the 3rd and 4th rows of scales, the dark spots (when present) are on the 3rd or 6th row of scales.

The coloration of juveniles is the same as that of adults. Color in life is thought not too different from that of preserved specimens, for notes on the color of living individuals (Neill and Allen, 1961:44) agree with what I have observed on preserved snakes.

_Remarks._--The specimen from "Peten" (USNM, no. 4941) is the only specimen that has a controversial history. As can be seen from the synonymy of the species, the relationship of this specimen with the rest of the genus has been interpreted in several ways. Smith (1941:122-123) stated that the above specimen was catalogued as being from El Salvador; however, the locality was presumed by him to be El Peten, Guatemala, due to the presence in the bottle of a piece of paper inscribed "_Conophis vittatus_, Peten, J. M. Dow." This specimen is the one mentioned by Cope (1861:300, 1876:76, and 1900:1094-95), and in the first paper is ascribed to Guatemala. In 1900 this specimen was named _C. lineaticeps_ by Cope who thought the specimen differed significantly from _C. concolor_ (Cope, 1867:318-319). This specimen has the coloration normal for _C. l. concolor_ as far posteriorly as mid-body; beyond mid-body the dark lines, typical of _C. l. lineatus_ or of _C. l. dunni_, are present. It is likely that this specimen is an intergrade between _C. l. concolor_ and _C. l. dunni_, the other subspecies present in Guatemala.

The only specimen not from the Yucatan Peninsula is allegedly from Patuca, Honduras (USNM 20271). It was obtained in the 1870's. Possibly more collecting will verify the presence of _C. l. concolor_ in northern Honduras. This individual may be merely a genetically aberrant specimen from an area where normal specimens are _C. l. dunni_. Neill and Allen (1961:44-45) suggested that the specimen from Patuca implies widely overlapping distributions for _C. l. dunni_ and _C. concolor_. The occurrence of _C. l. concolor_ in Honduras needs to be verified before this assumption is made. There can, therefore, at present be no objection to the view that intergradation between the subspecies _C. l. dunni_ and _C. l. concolor_ could occur through a relatively broad area of El Peten and British Honduras.

Neill and Allen (1961:44-45) further suggest that the present range of _C. l. dunni_ extends "presumably still farther northward toward the Mexican state of Veracruz where _C. l. lineatus_ exists." Actually the presence of the subspecies _C. l. dunni_ and _C. l. lineatus_ as presently disjunct populations implies merely that they were presumably a continuous population at some time in the past.

The characteristics of the genus in combination with the reduction of dark coloration posterior to the head distinguish this snake from all other snakes in Mexico and Central America.

_Distribution._--The Yucatan Peninsula: eastern Campeche, all of Yucatan, probably in Quintana Roo, and the northern third of British Honduras. A record for northeastern Honduras is questioned (fig. 2).

_Specimens examined._--Total of 48, as follows: BRITISH HONDURAS: _Belize District_: 13.0 mi. W, 1.5 mi. S Belize, ERA-WTN BH-1562.

GUATEMALA: _El Peten, no specific locality_, USNM 4941.

HONDURAS: _Colon_: Patuca, USNM 20271.

MEXICO: _Campeche_: Champoton, UMMZ 73063-66; Encarnacion, CNHM 106462. _Yucatan: no specific locality_, BMNH 80.7.13.30; Chichen Itza, AMNH 38826, 38833, CNHM 20610-11, 26986-87, 36299-300, 36303-04, 36307, 36316, MCZ 7422, 28748, UMMZ 68236, 73060-62, 80806, USNM 46395; Kantunil, CNHM 36301, 36305-06, 36308-09, 36312-13; _Libre Union_, CNHM 36298, 36302, 36310-11, 36314; Mayapan, CNHM 40720; Merida, CNHM 19411, 19413, NMW 16828; Progreso, CNHM 40721; Tekom, CNHM 49374; Yokdzonot, CNHM 36315.

=Conophis nevermanni= Dunn

_Coniophanes imperialis imperialis_, Wettstein, Sitz. Akad.
Wiss. Wien. mathem-naturw. Kl., 143:37-38, 1934.

_Conophis nevermanni_ Dunn, Copeia, no. 4:214, December 31,
1937; Smith, Proc. U. S. Natl. Mus., 92:395, November 5, 1942;
Savage, Trans. Kansas Acad. Sci., 50:484, December 31, 1949;
Taylor, Univ. Kansas Sci. Bull., 34(pt. 1): 145-146, October
1, 1951.

_Type._--Academy of Natural Sciences of Philadelphia, no. 22423, obtained by Emmet R. Dunn from Prof. Manuel Valerio. Type locality: Rio Poas de Aserri (a few miles south of San Jose), Costa Rica.

_Diagnosis._--Head and body dark brown or black above with two or four white stripes along body; usually two white lines on head immediately above eye passing from canthus rosetralis posteriorly to connect with white stripe on 6th row of dorsal scales; eight supralabials with black margins above.