12 PROCEEDINGS OF THE NATIONAL MUSEUM vol.76 



In the great abyssal depths the bryozoa generally appear to be 

 stunted. 



At the center there is no visible ancestrula, but there are four 

 zooecia in a cross. Each cell is perforated by six large opesiules. 

 On the inner side the ribs are smooth when the colony is little calci- 

 fied ; they are granulated on the much calcified colonies. 



All of our colonies were dead except one which had preserved its 

 avicularian setae. 



There exists a small variation conlca, in which the colony is very 

 small, full, and conical. It has been found in the Helvetian faunas 

 of Touraine. 



Biology. — This species has been dredged at very great depths, for 

 it is one of the rare species characteristic of the abyssal ooze. Be- 

 cause of its mobility it can live upon the moving bottom. The bathy- 

 metric dispersion rises only up to a depth of 80 meters and it can not 

 adapt itself easily to slight depths (Calvet, 1907). This statement 

 of Calvet on the bathymetric dispersion is a little exaggerated, for 

 it lives perfectly in waters of little depths, because Smitt discovered 

 it at Cape Fear River at a depth of only 11 meters. 



As it is very abundant between America and the Hawaiian Is- 

 lands at the great depth of 4,411 meters with a temperature of 1.4° 

 C. we may suppose it can exist in the boreal zone, but it is a species 

 of the tropical zone and does not generally extend far from the 

 Tropics. Neither the depth nor the temperature seem to modify its 

 biologic limits. 



Its locomotion facilities are much reduced and it is not able to 



Occurrence. — Galapagos Islands, D. 2815; Hawaii, D. 3813. 



Geographic distHhution. — Mediterranean: Oran, 87 meters. At- 

 lantic : Cape Verde Islands, 1,900 meters ; Canary Islands, 80 meters ; 

 Madeira, 81-113 meters; Florida, 29 fathom's; Tortugas, 12-22 fath- 

 oms; Beaufort, N. C; Cape Fear River, 7 fathoms. Indian Ocean: 

 Mergui Archipelago. Pacific Ocean : Between California and the 

 Hawaiian Islands, 2,723 fathoms. 



Cat. No. 8478, U.S.N.M. 



