ANTARCTIC BRYOZOA — ROGICK 233 



arise dichotomously at the yellow chitinous nodes. Articulation tubu- 

 late (see Busk, 1884, pp. 85-86; Hastings, 1946, p. 234). Crystal- 

 clear smooth thin-walled zooecia arranged in transverse series of five 

 around tlic branch. Sometimes tiny tubercles occur on the crypto- 

 cyst, set far apart. Zooecial walls salient, ribbonlike. Fertile zooecia 

 nearly rhombic, nonfertile ones liexagonal. Zooecial orifice cellariae- 

 form, very close to the distal arch of the zooecial wall. Its distal or 

 upper lip is hemispherical; lower lip faintly convex, with a condyle 

 at each proximal corner. Parenthesis-like chitinous rods at side of 

 zooecial orifice and also faint thin cryptocyst ridges present. Ovicells 

 broadly truncate distally, roughly quadrangular in front view. Ooeci- 

 opore oval or ellipsoidal. Avicularia vicarious, as large as the auto- 

 zoids which they replace in the transverse series. Mandible large, 

 triangular. The species is named for the transparent crystallike 

 beauty of its walls. 



Colony: The colony color is a translucent glassy white with a 

 slight yellow tint. Zooecia lightly calcified, nodes chitinous but 

 covered for a time at least by the calcareous zooecial bases (pi. 5,E). 

 The growth habit is like that of Cellaria moniliorata, free, erect, with 

 branching loose and dichotomous (pi. 4,D). The slender branches 

 range in length from 7 to 14 mm. Some colony fragments are 56 mm. 

 long but that is only part of the possible colony length. Articulation 

 is tubulate, a condition where the internal chitinous joints are straight, 

 yellow to amber colored tubes or cores covered by zooecial walls and 

 where the cluster of tangled radicle fibers is absent (pi. 5,E). 



Zooecia are arranged in successive linear transverse series of five 

 around the imaginary longitudinal axis of the branch (pi. 4,F,I). 

 Occasionally a branch will have a series of four zooecia but the 

 5-zooecia series is the rule. Successive series fit into each other in 

 zig-zag fashion so that if a transverse cut is made through a branch 

 in a midseries region the branch is 5-sided, but if made in the zig-zag 

 region the branch is 10-sided (pi. 4,F,I). A zoid opens out on each 

 face. Branches are quite uniform in diameter throughout their 

 extent and everywhere in the colony, ranging in thickness from 0.590 

 to 0.742 mm. (average 0.667 mm.). Even fertile, ovicelled branches 

 do not seem very much larger in diameter than nonfertile ones (com- 

 pare figures H and J of pi. 4). Areolation is nearly rhombic in 

 fertile branches but very regularly hexagonal in nonfertile branches 

 (pl.4,I,J). 



Zooecia: The surface faces of zooecia in nonfertile branches are 

 sharply hexagonal, with clear-cut razor-edge outlines (pi. 4,1). They 

 are longer than wide. The fertile zoids, because of the ovicells which 

 are buried under the side and front walls of neighboring zoids, assume 

 a more nearly rhombic or diamond shape in frontal aspect (pi. 5, A). 



