480 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



considerably inflated and rising sharply toward the peristome, with 

 numerous minute pores, the areolar pores usually obscured by later 

 calcification. The primary aperture is small, about 0.09 mm long by 

 0.12 mm wide, semicircular with a straight proximal border; the sinus 

 is narrow, deep and constricted and the proximal corners are definitely 

 notched. The peristome is somewhat elevated, thickened, completely sur- 

 rounds the aperture and bears about 6 oral spines. 



The striking feature of this species is the presence on either side 

 of the aperture of a peculiar avicularium, the mandible of which is 

 shaped like the foot of a goose ; there is a strong cross bar for the attach- 

 ment of the mandible. 



The ovicell is very short, small and prominent. 



Described by Smitt from Florida, it is found around the world in 

 warmer waters. The only record for the Pacific coast of the Americas 

 is that of Hastings from Gorgona, Colombia. 



Hancock Stations: 270, Angel de la Guardia Island, Gulf of Cali- 

 fornia; 307, Secas Island, Panama; 411-35, Gorgona Island, Colombia; 

 and 143-34, Wenman Island, 788-38, Dahpne Major Island, 155-34, 

 432, and 461, Albemarle Island, Galapagos. 14 to more than 100 fms. 



Mastigophora porosa (Smitt), 1873 



Plate 58, fig. 4 



Hippothoa porosa Smitt, 1873:41. 



Mastigophora porosa, C^nn and Bassler, 1928:134; 1928b :38. 



Zoarium encrusting in a single layer, flat and white, with very 

 conspicuous brown vibracula. Zooecia large, but very variable in measure- 

 ment, 0.60 to 0.80 mm long by 0.45 to 0.80 mm wide; the frontal a 

 tremocyst with minute pores and so flat that the zooecia are distinct 

 only in the youngest stages; there are a few very large areolar pores, 

 which usually become closed by secondary calcification. The primary 

 aperture is wider than long, 0.14 mm wide by 0.11 mm long, rounded 

 with a straight proximal border in which there is a v-shaped sinus; the 

 notches at the proximal corners, referred to by Smitt, are usually quite 

 distinct. The operculum is thin, with a triangular proximal tongue, and 

 of the same form as the aperture. 



The most striking feature is the large, elongate vibraculum, usually 

 more than 1.00 mm in length, one on every zooecium at the side of or 

 a little proximal to the aperture. 



"The ovicell is very short and of the same structure as the frontal" 

 (Canu and Bassler). Our specimens are not in reproduction. 



