8 PROCEEDINGS OF THE NATIONAL MUSEUM vol.76 



On the much calcified zooecia the opesium is smaller and the 

 cryptocyst more developed. A simple tuberosity then replaces the 

 distal avicularium. 



Affi7iities. — This species differs from Membrendoecium ovatum 

 Canu and Bassler, of the Philippines, in its smaller zooecia and its 

 finely crenulated opesium. It has much resemblance to M. trams- 

 verswm Canu and Bassler, 1920, of the American Midwayan and 

 differs only in the longitudinal orientation of the small avicularia. 

 It could perhaps be the same as M. papillatum Busk, 1884, of the 

 Philippines, in which the cryptocyst is granulated and the opesium 

 is regularly oval, but we have no other means of comparison than 

 the incomplete figure of the author. 



Biology. — The zoarium incrusts shells in many superposed lamellae. 

 The exterior lamella shows then false ancestrulse which are not 

 derived from a larva. The lamella directly in contact with the 

 shell has zooecia less calcified and more irregular. Our specimens 

 were in reproduction and fixation April 7, 1888, 



Occurrence. — Galapagos Islands, D. 2813 and D 2815. 



Cotypes.—Q^X. Nos. 8471, 8472, U.S.N.M. 



Family ALDERINIDAE Canu and Bassler, 1927 

 Genus CALLOPORA Gray, 1848 



CALLOPORA TENUIROSTRIS Hincks. 1880 



1918. Membranipora tenuirostris Waters, Some collectiou.s of the littoral 

 marine fauna of the Cape Verde Islands, Bryozoa, .Journal Linnean 

 Society Zoology, vol. 34, p. 9. (Bibliography, geographic distribution). 



1920. Callopora tenuirostris Canu and Bassler, North American Early Tertiary 

 Bryozoa, Bulletin 106, U. S. National Museum, p. 154, pi. 29, figs. 10, 11. 



1928. Callopo?-a tenuirostris Canu and Basslek, Fossil and Recent Bryozoa of 



the Gulf of Mexico Region, Proc. U. S. National Museum, art. 2710, p. 

 31, p. 3, fig. 4. 



1929. Callopora tenuirostris Canu and Bassleu, Bryozoa of the Philippine 



Region, Bull. 100, vol. 9, U. S. National Museum, p. 102, pi. 3, fig. 6. 



Our specimens incrust dead shells, oysters, Cellepores, Smiftina, 

 Nullipores, and Cupularia umbellata. For the greater part they are 

 living. 



Biology. — This is a species of shallow water and does not pass 

 beyond 90 meters. The Albatross, however, dredged a dead speci- 

 men in the Philippines at 379 meters. It is abundant in the equa- 

 torial or subequatorial zone, although it has been observed in the 

 temperature zone of the Pacific. 



It was in reproduction on January 30, 1885, in the region of the 

 Gulf of Mexico, and on April 7-9, 1888, in the Gallapagos Islands, 

 and in September 18, 1918, at La Jolla, Calif. 



Occurrence. — Galapagos Island, D. 2813 and D. 2815. 



