ANTARCTIC BRYOZOA — ROGICK 249 



'vard to attach to the substratum or other objects. The stalks 

 quickly widen into a very flat, bilaminate blade which is broad but 

 hin (pi. 10,B,C). Zooecia open out on the two faces of the frond. 

 The number of zooecia in a horizontal row on one face varies from 

 } to 18 (pi. 10,D,J). One of the fragments is dichotomously branched 

 3ut no joints or nodes were seen in it (pi. 10,B). Areolation is hexag- 

 onal (pi. 10,D,J). 



Zooecia: The visible frontal surface of the zooecia is hexagonal 

 md quite angular, measuring from 0.518 to 0.677 mm. (average 

 3.579 mm.) in length and from 0.310 to 0.432 mm. (average 0.372 mm.) 

 n width. However, there is more to a zooecium than this hexagonal 

 front. A considerable stretch of the proximal part of each zooecium 

 is hidden between the two zooecia directly below it (pis. 10,F; 11, B). 

 Therefore, the total length of a zooecium (including both the visible 

 and the hidden parts) ranges from 0.878 to 1.210 mm. (average 

 1.056 mm.). This hidden proximal part is long and narrower than 

 ■the visible frontal hexagon. The body cavity is long, narrow, and 

 somewhat spoon shaped in front view (pi. 10,F). 



The proximal-distal walls between successive zooecia are porous 

 (pis. 10,E; 11,C). One pore plate has 18 small pores, others have less. 

 i The cryptocyst varies from translucent to nearly opaque, is cal- 

 careous, covered with small, rather closely spaced tubercles (pi. 

 11,D), and is gently convex, depressed centrally about the zooecial 

 orifice. The orifice rim is slightly salient. The mural rims also are 

 thin, narrow, well defined sahent lines. Two distinct parenthesis- 

 shaped chitinous lines about the orifice curve slightly outward and 

 in reverse as they approach the center of the cryptocyst front (pi. 

 '10,F). Cryptocyst ridges, also parentheses shaped but on a larger 

 scale, are rather inconspicuous (pi. 11, D). 



' ZooEciAL orifice: The zooecial orifice is some distance away from 

 'the distal cornice of the frontal wall, in a depressed region of the 

 cryptocyst, and is somewhat crescent shaped but with the ends 

 'gently curved instead of sharply pointed (pi. 10,F, and or in pi. 

 11, D). It is about three times wider than its central line length 

 and about twice as wide as its all-inclusive, boxed-in length. Its 

 'dimensions are: over-all length from 0.094 to 0.130 mm. (average 

 '0.107 mm.); length in midcentral line from 0.058 to 0.072 mm. 

 (average 0.066 mm.), and width from 0.158 to 0.230 mm. (average 

 0.196 mm.). Its smooth rim is salient. The lower lip is curved 

 sHghtly outward like the lip of a pitcher. Two proximal condyles 

 'are inside the orifice. No distal teeth were seen. 



The operculum is the same shape as the orifice, which it fits snugly. 

 It is a translucent yeUow, with a pebbled surface (pi. 10,G). One 

 of the marginal zooecia (along the edge of the blade) has an unusually 



