306 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



rolled front. When an umbo is present (pi. 32,D,G,H,J) it may 

 resemble an abbreviated spout. It is granulated, broadly rounded, 

 with its base surrounded by a row of 3 to 6 widely spaced tiny pores 

 (pi. 32,E). 



About 5 to 7 pore plates occur in the lateral walls. 



Avicularia: Only one kind of avicularium was found. It is almost 

 always present and always in the same location, within the peristome 

 border, median, proximal and just external to the lyi-ula. It is small, 

 elliptical, and set into the peristomie in a plane vertical or at right 

 angles to the frontal plane. Its mandible is hemispherical and chitin- 

 reinforced both around the periphery and about the median lucida. 



Orifice: The shape but not the size of the secondary orifice is 

 different from that of the primary orifice. The secondary orifice is 

 roughly hoe shaped — a round-cornered rectangle whose basal line sags 

 a bit downward to accommodate the oral avicularium. The peristome 

 is slight. The primary orifice is somewhat elliptical. Two blunt 

 cardelles project laterally toward the medium-sized lyrula. A lightly 

 chitinized operculum closes the primary orifice. It is wider distally 

 than proximally. 



Ovicell: The salient ovicells when seen from the front are globose. 

 In side view their porous frontal is somewhat flattened. Their primary 

 calcareous layer is shiny, smooth, entire except for the front face which 

 is punctured by a number of small uTegular pores. The secondary 

 peripheral layer is thicker, rough, granular to pebbly, nonporous, 

 and horseshoe shaped. It encroaches upon the sides and distal rim 

 of the primary layer, leaving exposed the porous frontal area of the 

 latter. Where the colony is heavily calcified the zoid frontal wall 

 thickens very much as does the encircling crust around the ovicell 

 but the perforated plate over the front of the ovicell remains fragile, 

 thin and porous, w ith the yellow to brownish embryos shming through 

 (in colonies from Station 234 especially) . Raised mural rims may be 

 seen traversing the peripheral layer (cf. pi. 32,A). 



Distribution" and ecology: Two large handsome colonies (pi. 

 32,B,I) and a few scraps came from Station 234. Smaller fragments 

 came from Stations 226 and 230. The two large colonies had other 

 forms growing on them or on then* dorsal surface — sponge spicules, 

 calcareous worm tubes, Ramphonotus inermis, Beania, etc. 



Marcus reported the species from Isle of Palmas, Santos, Brazil, 

 remarking that it grew on algae and solid substrates (1937, pp. 109-110). 



Brown reported S. acaroensis (the part recorded in foregoing syn- 

 onymy under S. evelinae) from fossil deposits collected at Castlecliff, 

 New Zealand (1952, pp. 330-331). 



Affinities: The Antarctic specimens very closely resemble in gen- 

 eral appearance those of Brown and Marcus but differ from those of 



