NO. 1 OSBURN: eastern pacific BRYOZOA — CHEILOSTOMATA 27 



It is an abundant species along the Atlantic coast from Cape Cod to 

 Brazil, in shallow water along the shores and entering estuaries where 

 the salinity may be reduced to less than one-half that of sea water. It 

 does not appear to be as abundant an5rwhere on the Pacific coast. Busk's 

 material of denticulata came from Mazatlan, Mexico, and Hastings 

 recorded it from several localities in the Canal Zone and from the Ga- 

 lapagos Islands. Probably because it is a shallow water species it did not 

 appear frequently in the Hancock dredgings, as it was not taken below 

 16 fathoms. 



Fairly common along the coast of southern California and down the 

 west coast of Lower California; at Stations 1044-40 (Tiburon Island), 

 1049-40 (Angel de la Guardia Island) and 1071-40 (San Felipe Bay) 

 in the Gulf of California; Station 374-35 at Independencia Bay, Peru. 

 Also at Acapulco Bay, Mexico, specimens collected by Captain F. E. 

 Lewis. 



Membranipora savarti (Audouin), 1826 

 Plate 2, fig. 7 



Flustra Savartii Audouin, 1 826 :240. 



Biftustra Savartii, Smitt, 1873 :20. 



A canthodesia savartii, Canu and Bassler, 1920:100; 1930:4. 



A canthodesia savartii, Marcus, 1937:40. 



Acanthodesia savarti, Osburn, 1947 :9. 



The zoarium is erect, with narrow ligulate or bifurcate bilaminate 

 fronds rising from an encrusting base which may spread over an area of a 

 square centimeter or more. The zooecia of the erect fronds are regularly 

 elongate-quadrangular, moderate in size, the walls rather heavily calci- 

 fied and granulated. The cryptocyst forms a horizontal shelf at the 

 proximal end with a denticulate process projecting into the opesia, and 

 there are also denticles projecting from the narrower lateral cryptocyst. 



The proximal horizontal dentate process of the cryptocyst is a very 

 striking character when it is present, and the genus Acanthodesia was 

 founded on it. However it is very often wanting entirely, or present on 

 only a few zooecia of a colony. I have failed to find any evidence of it 

 in Pacific coast specimens which otherwise agree perfectly. On the other 

 hand, Silen (1941:19) found "the proximal denticle prominent in all 

 specimens" from the Bonin Islands, Japan. 



It is a common species around the world in warmer shallow waters. 



Dredged at 14 Hancock stations: off Point Loma, California; Tibu- 

 ron Island, Gulf of California; Lower California at Dewey Channel 



