342 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



bottoms affect the coloration and appearance of the specimens but the 

 data are not adequate to warrant positive statements. The evidence of 

 hybridization with Brisaster has been presented under the discussion of 

 Brisastcr ton'nsendi. 



Distribution.— Tht fact that Brissopsis was taken at 65 stations is evi- 

 dence of its general distribution, but an analysis of the data shows that 

 nearly all the material is from moderately deep water off the coast of 

 California, particularly in the vicinity of the Channel Islands. Speci- 

 mens were secured near Clarion Island, but the most notable extension 

 of the range is the taking of 2 small but indubitable specimens at Station 

 786-38, northeast of Indefatigable Island in the Galapagos Islands, in 

 392 fms. 



Type.—M.CZ. no. 3063 (Cotype). 



Type locality. — Albatross Station 3355, off Point Mala, Panama, 

 182 fms. 



Depth. — 5-39 fms. 



Specimens examined. — 674 specimens from 65 stations. 



Plagiobrissus pacificus H. L. Clark 

 Plate 66, Figs. 68-70 



Plagiobrissus pacificus H. L. Clark, 1940, p. 351, pi. 2, figs. 3, 4. 



The occurrence of this rather striking Spatangoid in the Gulf of Cali- 

 fornia is of great interest as it was known hitherto only from the ty^pe 

 and paratype taken on Hannibal Bank, Panama, in 35 fms. In the Velero 

 collection there are 67 specimens of this interesting Spatangoid, of which 

 9 are large enough to be called adults, but the test is thin and fragile and 

 4 are more or less crushed. The smallest is 10 x 7.5 x 4.5 mm and is quite 

 undamaged. The largest is 56 x 41 x 20 mm, thus much larger than the 

 holotype. Several specimens have a gray tint to the test instead of brown 

 and there is a great deal of diversity as to the degree of brownness. While 

 the general tuberculation and the arrangement of fascioles agree well with 

 Mctalia, the shape of the test is quite different from the short thickset 

 form of most of the known species of that genus, and the large tubercles 

 in intcrambulacra 1 and 5 show conclusively that it is not that genus. 



Distribution. — All the material of Plagiobrissus was taken in the Gulf 

 of California at depths of 5 to 75 fms except 3 specimens, as follows: a 

 single fine bare test from Station 948-39, which is in Panama Bay in 30-35 

 fms; a very good half-grown specimen from Station 773-38, which is off 

 Nuez Island, Cocos Island, in 31-50 fms ; and a damaged young individual, 

 14 mm long, whose identification is somewhat dubious, from Station 212- 



