

ANTARCTIC BRYOZOA — ROGICK 297 



Z-L, 1.440-1.92 (1.744) Se-Or-W, 0.187-0.216 (0.206) 



Z-W, 0.440-0.520 (0.488) Pr-Or-L, 0.144-0.173 (0.153) 



,Av-L, 0.331-0.360 (0.350) Pr-Or-W, 0.202-0.216 (0.215) 



Av-W, 0.115-0.130 (0.129) Ly-L, 0.029-0.043 (0.032) 



B-L, 0.259-0.266 (0.265, three readings) Ly-W, 0.101-0.122 (0.110) 

 S^Or-L, 0.173-0.230 (0.203) 



Ij Zoarium: Ivory-colored, flat and smooth. One colony fragment 

 appears to be bilaminate. 



Zooecia: a thin salient edge outlines the boundaries of the long, 

 narrow, boxlike zooecia. Various kinds of zooecia are present: ovicelled, 

 nonovicelled, and those Avith or without avicularia. The raised, collar- 

 like peristome is the most elevated part of the zooecial front. The 

 frontal wall is slightly convex and much thicker than the flat lateral 

 and back walls. It is a tremocyst perforated by small, irregularly 

 scattered and widclj^ spaced pores, not areolate in nature. Deviations 

 from this condition occur in some zooecia through gi^eater calcification, 

 which leads to an almost complete obliteration of the pores or to a 

 roughening of the frontal surface by low bumps, closely set together. 

 Lateral walls are punctured by four or five large pores. The proximal 

 wall has two pores. 



Avicularium: Not all zooecia have avicularia. In one colony only 

 3 out of 29 zoids had avicularia. Not more than one occurs per zoid. 

 All the observed avicularia are of one type, long, narrow, spatulate; 

 and in one location, suboral, external, median. They are oriented 

 with the mandible pointing proximally, are placed close to the peri- 

 stomial notch, and are rounded at both ends. Their long sides are 

 parallel. Their proportion of length to width is almost 3:1. No 

 mandibles are available. 



Orifice: The orifice is practically terminal, at the distal-frontal 

 edge of the zoid. A raised peristome arches about tliree-fourths of the 

 way around the opening. The other fourth is the notch or interruption 

 in the peristome. Deeper within the peris tomie is the primary 

 aperture. 



The secondary aperture is nearly circular, except for the notch or 

 gap. The peristomia.1 wall is formed cooperatively by its own and 

 adjacent distal zoid (pi. 28, G). The primary orifice is smittinoid, 

 gently arched distally; proximally it has a wide low median lyrula, 

 some distance to each side of which is a wedge-shaped cardelle. 



Opercula unobserved. 



Ovicell: Only two easily distinguishable ovicells are in the 

 samples. They are somewhat flattened, globose, and perforated by a 

 few irregular pores. They did not have an avicularium suborally, but 

 whether this is a constant or variable feature cannot be determined 

 because of lack of material. 



