260 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



(pi. 5, fig. 2a). However, C. rossi and C. foveolata differ in type of 

 suboral aviciilaria and in mandibular shape, and the mucros seem to 

 be absent from C. foveolata, at least they are not mentioned or figm-ed 

 by Waters. 



The distal border of the primary orifice and the peristome arch in 

 a neat semicircle. The proximal border of the orifice is distorted by 

 the vertical-diagonal oral ledge (pi. 13,E,K) which interrupts it 

 and helps to form a channeled gi'oove that leads down from the orifice 

 corner toward the nearest mucro (pi. 13,1). When the colony is old 

 and the mucros, oral ledge, and oral channel well developed, the 

 orifice looks very asymmetrical because one corner of it is pulled 

 downward out of shape by the channel (pi. 13,B,I). 



Dimensions of primary orifice: length 0.166-0.230 mm. (average 

 0.202 mm.); width 0.216-0.288 mm. (average 0.229 mm.). 



OvicELLs: Ovicells are present on some zooecia (pi. 13,H), absent 

 on others (pi. 13,1). They are globose, covered over by the secondary 

 calcified frontal layer and so are not easily distinguished from the 

 surrounding zooecial fronts. Although pores may be present around 

 and over much of the ovicell they do not perforate the ovicell frontal 

 wall. Sometimes the pores outlining or over the ovicell may be 

 larger than surrounding ones but that is not constant. Measurements 

 of five ovicells: length about 0.259-0.331 mm. (average 0.288 mm.); 

 width about 0.288-0.432 mm. (average 0.360 mm.). 



Types: Holotype, USNM 11229; paratypes, USNM 11230. 



Ecology: This species was collected at Antarctic Stations 44 and 

 104, off Cape Koyds, Ross Island. No other species grew on the 

 "living" colonies but dead colonies had some encrusting cheilostome 

 and cyclostome Bryozoa. Some of the external avicularial mandibles 

 were clamped tightly shut over long, fine, delicate rods which were 

 either of sponge or alcyonaria. 



Cellarinella nutti, new species 



Plate 14 



Diagnosis: Zoarium nodulated, bilaminate, flattened; seemingly 

 transitional between the tapelike and slab species. Branching 

 dichotomous. Internal avicularium transversely placed across the 

 inner frontal wall at the level of the orifice so that its side wall shows 

 readily from the outside. External avicularium, when present, 

 points obliquely down and forward. Frontal oral ledge tangentially 

 placed at side-back of the internal avicularium, high enough to show 

 from the front. "Naked" back mucro near midline and nearest the 

 orifice; forward, aviculariate mucro farther away from the midline 

 and from orifice. 



