﻿434 PROCEEDINGS OF THE NATIONAL MUSEUM vol. i02 



The nephi'idia vary in length, sometimes reaching to the origin of 

 the ventral retractors. The proximal third or half is anchored by a 

 mesentery. They open between the third and fourth longitudinal 

 muscles at the same level as the anus. A short distance in front of 

 them the muscle bundles unite to form a single sheet. The contractile 

 vessel is very slender, without villi. The brain has two eye spots. 

 The eggs are elliptical, 0. 1 1 by 0.09 mm. Each end is slightly truncated, 

 with an indentation in the thick shell. 



Type Zoca/%.— Philippine Islands. 



Distribution. — Indo-Pacific, tropical. The paucity of records as 

 compared with Ph. scolops is probably due to the habits of dentigerum 

 in hiding in crannies of coral rock. 



Specimens examined. — As follows : 



El Pulmo Reef, Baja California, southeast shore of end of peninsula, in inter- 

 stices of living coral, Pocf/Zopora, March 19, 1940, E. F. Ricketts, 10 specimens, 



Puerto Escondido, Gulf of California, Baja California, under boulders, March 25, 

 1940, E. F. Ricketts, 1 specimen. 



San Carlos Bay, Gulf of California, Baja California, among rocks, March 30, 1940, 

 E. F. Ricketts, 17 specimens. 



Puerto Refugio, Angel de la Guardia Island, Gulf of California, Baja California, 

 April 2, 1940, E. F. Ricketts, 2 specimens. 



Puerto Penasco, Mexico, Dec. 24, 1947, W. II. iNIacGinitie, 15 specimens. 



Panama Bay, Panama, F. H. Bradley, 1866, 3 specimens. 



Uemarks. — -This species varies considerably in ground color, which 

 is usually light brownish or grayish, and in the intensity of brown on 

 the introvert. I have examined specimens from Eniwetok Atoll, 

 Marshall Islands, Plawaiian Islands (Laysan, Kauai, Hawaii) and from 

 the Gulf of Davao, Mindanao. The extent of development of the 

 toothlike tubercles of introvert varies greatly. In the Laysan speci- 

 men they are symmetrical, sharp cones, as in some of the Baja Cali- 

 fornia examples. The tubercles of the ventral side of the introvert 

 and the papillae of the trunk are much larger in the Laysan specimen. 

 The specimens described above probably constitute a distinct race 

 inhabiting the Pacific coast within the tropics and subtropics. 



Ten Broeke (1925, p. 88) has described from Caracas Bay, Vene- 

 zuela, Phascolosoma microdentigerum, which differs from dentigerum 

 in the smaller size of its spines and the presence of little villi on the 

 contractile vessel. Trunin only 10 mm. long. Fischer (1922b, p. 11) 

 records dentigerum from Barbados, reef. 



PHASCOLOSOMA ANTILLARUM Grube and Oersted 



Plate 39, Figures 8, 9 



Pliascoloso77ia antillarum Grube and Oersted, 1859, p. 117. — Keferstein, 1865b, 



p. 4.35, pi. 31, fig. 11, pi. 33, fig. 37. 

 Phymosoma antillarum Selenka, 1883, p. 57, pi. 7, fig. 93-96. 

 Physcosoma antillarum Gerould, 1913, p. 420, pi. 62, figs. 19, 20.— Steinbeck 



and Ricketts, 1941, p. 346. pi. 16, fig. 2. 



