ANTARCTIC BRYOZOA — ROGICK 243 



'10,D; 11,D). It is a bit difficult to decide just where to take the 

 length and width measurements of Cellariaeforma parvimuralis 

 avicularia because of the difference in orientation of the lengthwise 

 direction of the mandible and of the outer avicularial surface. In 

 other words, the longitudmal axis of the mandible does not coincide 

 with the longitudinal axis of the rest of the avicularium (pi. 7,H), 

 Where it is uncertain as to which is the length and which is the width, 

 these terms will not be used; instead, the more suitable terms "longer 

 diameter" and "shorter diameter" will be used. Measurements for 

 the whole visible avicularium were obtained from only three speci- 

 mens: longer diameter from 0.230 mm. to 0.288 mm. (average 

 0.259 mm.); shorter diameter from 0.216 to 0.259 mm. (average 0.230 

 mm.). The outer avicularial opesia or opening measures 0.072 to 

 0.094 mm. (average 0.079 mm.) in length and 0.158 to 0.187 mm. 

 (average 0.178 mm.) in width. The proximal median notch of the 

 inside avicularian opening measures 0.029 to 0.043 mm. (average 

 0.034 mm.) in length and 0.043 mm. in width. The shape of the 

 avicularia is a bit hard to determine because of so little material but 

 i those few examined seemed pentagonal and wedged between four 

 ' zoids. The outer avicularian opening is spindle shaped but deeper 

 within it is a proximal ledge which has a sizable notch in it (pi. 7,C). 

 ' Mandibles were not observed. The avicularian openings are oriented 

 diagonally with respect to the longitudinal axis of the zooecia. 



Radicles: These may arise singly from the zooecial front but 

 some zoids have as many as two or three coming through the crypto- 

 cyst and growing proximally (pi. 7,F). They are chitinous, sturdy, 

 yet of small diameter, from 0.050 to 0.079 mm. (average 0.059 mm.). 



Types: Holotype, USNM 11217; paratypes, USNM 11218. 



Ecology: Only seven small fragments of this species were collected 

 from Antarctic Station No. 104. Some of the colonies were invaded 

 by large dark Folliculina-like protozoans whose shells protruded from 

 the bryozoan's zooecial orifices. Another growth proved to be 

 a cyclostomatous bryozoan. 



Genus Mawsonia Livingstone, 1928 



Diagnosis: Colony consists of a cylindrical sprig which may 

 branch dichotomously. Internodes fused. Zooecia arranged in 

 series around the longitudinal axis of the sprig. Zooecial walls flare 

 outward noticeably around the depressed cryptocyst, framing it like 

 a picture. Orifice longer than wide, a truncate oval, its distal end 

 steeply arched, its proximal end flattened and provided with two 

 conspicuous condyles at or near the corners. Avicularia generally 

 large, vicarious, with a more or less sharply pointed long beak and 

 mandible. 



