20 PROCEEDINGS OP THE NATIONAL MUSEUM vol.72 



Measurements. — Opercular valve: Zo = 0.30 mm. 



fZs = 0.90-1 .00 mm. 

 Zooecmmi, „ „_ „ .„ 



IZ2 = 0.35-0.40 mm. 



Affinities. — The ovicelled zooecia have the larger dimensions; the 

 mural rim bears a pair of spines. This species is well characterized 

 by its large ovicell. 



Occurrence. — Albatross Station D. 2750, off Chili, South America; 

 18° 30' N.; 63° 31' W.; 496 fms.; fine gray sand. 



Coty^es. —Csit. No. 7499, U.S.N.M. 



Family HINCKSINIDAE Canu and Bassler, 1927 

 Genus APLOUSINA Canu and Bassler, 1927 



Membraniporae with endozooecial ovicell; no spines, no avicula- 



rium, and no dietellae. 



Genotype. — Aplousina gigantea Canu 



and Bassler, 1927. 



1 Range. — Miocene — Recent. 



APLOUSINA GIGANTEA Canu and Bassler, 1927 



Plate 2, Figure 6, text Figure 3 



1927. Aplousina gigantea Canv and Bass- 

 lee, Classification Cheilostomatous Bryozoa. 

 Proc. U. S. Nat. Mus., vol. 69, p. 3, pi. 1, fig. 1. 



Description. The zoarium encrusts 



r, o A . o x,T, .XTT. shells. The zooecia are very large, 



Fig. 3.— APLOUSINA gigantea Canu and "^ » ' 



Bassler, 1927 diagkammatic drawing lozengc-shaped, not Separated from 



OF A zooEciuM, X 85, SHOWING THE TEN- , othpr' thfitniirfll rim i\ vprv thin 



TAcuLAR SHEATH ATTACHED TO THE OPER- ^acu otncr, lue murai Tim IS very inm, 



cuLAR VALVE. THIS 13 FIXED TO AN fihform. The opcrcular valve is large, 



EXTERIOR THICKENING OF THE ECTOCYST -it , • i i i 



transverse, semilliptical and removed 

 from the distal border of the zooecium. The ovicell is very small, 

 transverse, little salient, ornamented with a small frontal callosity. 



Measurements. — Opercular vaiveU ~q '^o ^^ ' 



rj ■ fZ2 = 0.84-0.90 mm. 

 Z««^^1^|Z3 = 0.60-0.64 mm. 



Structure. — The tentacular sheath is attached to the sclerite which 

 borders the opercular valve. The length of the tentacles is half that 

 of the zooecia. The parietal muscles are numerous. This species is 

 larger than the Miocene species, A. (Memhrendvecium) grandis, Canu 

 and Bassler, 1923. 



Biology. — We have observed this beautiful species only on the 

 coast of Florida, where it appears abundant. It was in reproduction 

 March 15, 1885, and April 9, 1886. Its large dimensions, the tenuity 

 of its tentacles, and the absence of avicularia indicate that it lived 

 especially in localities where a marine current incessantly renewed 

 the plancton. 



