I 



ANTARCTIC BRYOZOA — ROGICK 267 



0.287 mm.), width 0.288-0.389 mm. (average 0.341 mm.). The 

 front of the ovicell encroaches on the peristomeal passageway, as 

 shown in side view in plate 17, C and in front view in plate 17,B. 



Ovicell: Ovicells are globular and not easily distinguished exter- 

 nally except for their frontal wall, which intrudes upon the orifice 

 (pi. 17,B,C). Measurements for ovicell interiors: length 0.360- 

 0.504 mm. (average 0.428 mm.), width 0.331-0.432 mm. (average 

 0.370 mm.). 



Tentacle number: Some zoids were killed in an expanded condi- 

 tion. Their extended tentacles were dried on the colony surface, 

 around the orifice. The tentacles numbered 20 on one zoid and 

 approximately that, so far as could be determined, on a second. 



Types: Holotype, USNM 11239; paratypes, USNM 11240. 



Ecology: This species was collected at Antarctic Stations 104, 

 190, and 234. Some of the living fragments were encrusted with a 

 sponge, some with other Bryozoa such as Barentsia discreta, Phylactella 

 lyrulata, and Smittina sp. 



Cellarinella laytoni, new species 



Plate 18 



Diagnosis: Zoarium somewhat cylindrical but with a definitely 

 serrated appearance caused by the excessively large mucros. Occasion- 

 ally nodulated. Branching sparse. Zooecia open on all sides of the 

 stalk. Two unusually prominent mucros, one at each proximal 

 corner of the orifice, form a projecting platform below and in front 

 of the orifice. Frontal ridges converge toward the mucros. One 

 mucro supports the external avicularium., on its median side. External 

 avicularium beak points transversely outward or slightly distally 

 (upward). Internal avicularium obliquely placed below one corner 

 of the orifice within the zooecium, its curved beak just barely visible 

 from the outside. Frontal oral ledge reduced, barely recognizable. 

 Mandible of external avicularium longer than wide and not so strongly 

 hooked at the tip as is the internal avicularial mandible. 



The species is named in honor of Air, Layton, who assisted Comdr. 

 Nutt in the collection of some of the Bryozoa. 



Zoarium: The collection yielded nine ivory-colored fragments, of 

 which the longest is 27 mm. Some are about 2 mm. in diameter. 

 The sprigs have a jagged or serrate outline because of the huge pro- 

 jecting mucros (pi. 18,A,B). Zooecia open on all sides (pi. 18,E), 

 Nodes (pi, 18,F) are more frequent or recognizable in the younger 

 than in the older fragments. The colony surface is pitted with 

 channeled pores as in the preceding species. In some places, especially 

 about the mucros, converging ridges groove the surface (pi. 18,A,C). 



