236 ALLAN HANCOCK. PACIFIC EXPEDITIONS VOL. 8 



the mainland coast nearly all the specimens at hand were taken along 

 shore, very rarely in more than 2 fms. 



Type.— M.C.Z. no. 635 (Cotype). 



Type locality. — ^Acapulco, Mexico. 



Depth. — Shore to 57 fms. 



Specimens examined. — 191 specimens from 38 stations. 



Astropyga pulvinata (Lamarck) 



Plate 39, Fig. 9 



Cidarites pulvinata Lamarck, 1816, p. 59. 

 Astropyga pulvinata L. Agassiz and Desor, 1846, p. 345. 



Mortensen, 1940, p. 197, pis. 20-23. 



One of the characteristic Echini of the warmer Eastern Pacific, this 

 handsome sea-urchin is well represented in the Velero collections. There 

 are altogether 165 specimens, ranging in size from 5 mm h. d. with 

 primary spines 7 mm long, to adults 100-117 mm in diameter. The 

 diversity of color is very striking but is brightest in the young which are 

 often very handsome and dullest in the adults. The largest specimen in the 

 present collection is dry and measures 117 mm h. d. and about 40 mm v. d. 

 It is uniformly dark (almost black) above save for the usual large triangu- 

 lar interradial spots which are light buff but were probably white in life. 

 Apparently this represents the form collected by Mortensen at Contadora 

 Island, Panama, which he designates as variety venusta Verrill. The 

 present specimen was taken in 15-20 fms in Tangola Tangola Bay, 

 Mexico, in company with 3 specimens 70-90 mm h. d. which are all 

 tjTical, handsomely variegated pulvinata, as are many other Mexican spec- 

 imens. A very fine specimen, however, from Tiburon Island, Gulf of 

 California, 10 fms, is almost completely dark violet above, the interradial 

 spots being scarcely distinguishable and the lower surface being very 

 markedly suffused with violet. This is the most heavily pigmented speci- 

 men in the collection though only about 90 mm h.d. Young specimens 

 (17-35 mm) from the Gulf of California, Panama, and Ecuador are 

 verj' handsome in their variegated liveries of bright red, violet and yellow. 

 It does not seem to me desirable to give varietal names to any of the varied 

 forms, even though such extremes as venusta may be recognizable. 



Distribution. — This sea-urchin was taken by the Velero at some 16 

 stations along the Mexican and Central American coasts in depths down 

 to 20 fms though many collections were made along shore. The northern- 



