ANTARCTIC BRYOZOA — ROGICK 259 



Two colonies obviously collected in a living state were covered with 

 a thin, light tan, parchment membrane. The frontal pores and 

 channels were plugged with a brown substance. The membrane was 

 stretched tightly over the colony in dried specimens. It apparently 

 wears off or disintegrates from dead colonies. 



Avicularia: Internal avicularia, though present, cannot be seen 

 from any position on the outside because they are placed below and 

 laterally to the run of the orifice and because theh beak is turned more 

 laterally than obliquely, so the wall must be broken away to see them. 

 The internal avicularium is a pointed oval witli a triangular mandible 

 that has a hooked tip. It has a hooked beak like the external avicu- 

 larium although plate 13,E does not show it developed yet. The 

 mandible closely resembles those of the external avicularium (pi. 

 13,F,G). Dimensions of one internal avicularium: total length 0.158 

 mm.; total width 0.101 mm.; beak length 0.101 mm. 



The external avicularia are sharply pointed ovals cradled between 

 two mucros below and to one side of the orifice (pi. 13,D,I-K). 

 The two mucros vary in size; sometimes one, sometimes the other, is 

 larger. One mucro is nearer the orifice corner than the other. The 

 back area of the external avicularium rests against its base. The 

 other mucro pushes the avicularial beak forward and tends to sur- 

 round the avicularium, building up its walls (pi. 13,J,K). The ex- 

 ternal avicularium is always below and to one side of the orifice. Its 

 beak usually points at about a 30° angle away from the lower edge of 

 the orifice (pi. 13, K). External avicularium dimensions: total length 

 0.202-0.346 mm. (average 0.291 mm., based on 20 readings); total 

 width 0.130-0.288 mm. (average 0.206 mm., from 20 readings); beak 

 length 0.122-0.245 mm. (average 0.187 mm.); mandible length 0.108- 

 0.144 mm. (average 0.123 mm.); mandible width 0.094-0.144 mm. 

 (average 0.126 mm.). An old worn sample from which plate 12, K 

 was drawn has some rather large external avicularia and also some 

 smaller ones as in plate 13, D. An occasional avicularium points not 

 downward but as in plate 13, J. 



Frontal oral ledge: The oral ledge extends diagonally across 

 the proximal border of the orifice at a greater angle with respect to the 

 plane of the orifice and the internal avicularium (pi. 13,E,K) than in 

 any ot the other five new species. 



Orifice: The most conspicuous feature of this species is the pro- 

 jecting visorlike peristome which shades the orifice (pi. 13,H-J). It 

 may be worn down or broken off in some specimens, as happens also 

 to the mucros. The peristome protects the three sides of the orifice. 

 No zoids were found in which the peristome completely encircled the 

 orifice. Waters (1904, p. 57) mentioned a "raised cap over the distal 

 end" of the oral aperture of Cellarinella foveolata and also pictured it 



