Chapter II: CLATHROPTYCHIUM, Rost. Æthalium composed of numerous regular erect

sporangia, seated in a single compact stratum, on a well-developed hypothallus, the surface formed by the coherent apices. Sporangia at first cylindric, with the apex convex and the wall entire; soon, by mutual pressure, they become prismatic and the lateral faces disappear, leaving the edges and the apex permanent. Spores globose, ochraceous.

1. CLATHROPTYCHIUM RUGULOSUM, Wallr. Æthalium composed of numerous very slender sporangia, closely compacted into a single stratum, and seated on a conspicuous silvery hypothallus; the surface ochroleucous, honey color or olivaceous. The sporangia are typically hexangular when the lateral faces disappear, leaving at the edges six simple triangular threads, extending from the angles of the hexagonal apex downward to the base. Spores in the mass ochraceous, yellowish or brownish, globose, minutely warted, 8-10 mic. in diameter.

Growing on old wood. Æthalium somewhat circular, or often quite irregular in shape, 1 to several centimeters in extent, the individual sporangia nearly 1 mm. in height, but scarcely .1 mm. in thickness. Deviations from the typical form of the sporangia sometimes occur, they are not seldom pentangular, and I have seen the apices quadrangular, with only four threads, or even triangular, and with but three; the threads, too, are said occasionally to branch and anastomose. _Reticularia plumbea_, Fries, S. M. III, 88; and _Ostracoderma spadiceum_, Schw., N. A. Fungi No. 2,381.