I ANTARCTIC BRYOZOA — ROGICK 281 



I Zoarium: The ivory-colored zoarium forms a dense crust on rocks, 

 ■"'he convexity of the individual zooecia gives it a bumpy appearance. 

 Che largest colony is 3 cm. in diameter. 



Zooecia: The large, distinctly outlined hexagonal zooecia have a 

 hick frontal that is a smooth areolate olocyst covered by a closely and 

 »eautifully beaded areolate plem-ocyst. It is convex, sloping upward 

 rom all sides to the elevated peristome. A row of rounded, regularly 

 paced areolar pores is set close to the thin mural rim. The frontal 

 )etween the pores is not noticeably ribbed. The rest of the frontal 

 urface is not porous. The compensation sac area occupies about 

 our-fifths of the inner zooecial frontal surface. On the under zooecial 

 urface from three to five (usually four) large oval dietellae are present 

 n the distal half of the zoids. 



Avicularia: One to three broadly elliptical avicularia may occur 

 »n some zoids, or be entirely absent. They are always peripheral in 

 ocation, developing on the corner areolar pores and not occuning 

 ilsewhere on the frontal (pi. 21,D,E). The avicularial chamber is 

 imall. The short, broad, thumb-nail shaped mandibles are reinforced 

 ')y a wide chitinous border and always oriented outward, toward the 

 looecial periphery (p. 21,G). The beak is slightly longer than the 

 nore hemispherical back area (pi. 21,B,C). 



Orifice : The frontally elevated orifice is a short distance from the 

 zooecial distal border. A collarlike peristome hides much of the pri- 

 nary orifice, which is hemispherical, smittinoid, and provided 

 vith a low medium-wide lyrula and cardelles. The hemispherical 

 operculum has lateral sclerites (pi. 21,H,I). There is no oral avicu- 

 arium. The peristomial collar is broadly notched frontally in two 

 places. Between these two gaps it rises into a lip or mucro (pi. 21,D). 

 tn nonovicelled zoids the collar is complete distally, but in ovicelled 

 iooecia the ovicell interrupts it (pi. 21,D). 



Ovicell: The salient, globose, nonporous ovicell has a beautifully 

 beaded surface. It is outlined by a row of areolar pores which perforate 

 the frontal of the surrounding zoid but not the ovicell itself. Neither 

 the peristome nor the walls of the neighboring zoids encroach upon its 

 surface. 



Distribution and ecology: The holotype of this species (USNM 

 11296) is from Station 184 (Marguerite Bay); paratypes were found 

 on Rocks 8, 18, 19 (stations unknown). Numerous Foraminifera are 

 incorporated into the zooecial bases or overgrown by specimens from 

 Rock 19. Some of the zooecia have several brown bodies inside. 



Affinities: This is a handsome species, reminding one more of 

 the genus Mucronella than of Smittina except for the presence of the 

 avicularia. 



