NO. 5 CLARK: ECHINI OF WARMER EASTERN PACIFIC 297 



Clypeaster ochrus H. L. Clark 

 Plate 47, Fig. 27 



Clypeaster ochrus H. L. Clark, 1914, p. 30, pi. 141, figs. 1-3. 



There can be no doubt of the close relationship between this species 

 and speciosus but after a prolonged studj^ of all the Velero Clypeasters, it 

 seems best to maintain ochrus as at least an incipient species. Typical speci- 

 mens in good condition are easily recognized, but immature or badly pre- 

 served individuals cause trouble. Moreover well-preserved specimens of 

 the two species may be so much alike in color that it is very hard to deter- 

 mine to which species they belong but the greater height of the test with 

 its somewhat greater concavity can usually be relied upon to distinguish 

 ochrus; in speciosus, the height is about one-fifth of the length, in ochrus 

 it is one-fourth. In the Felero collection, there are 47 Clypeasters which 

 may be referred to ochrus. They range from 5 to 114 mm in length but 

 the most typical is 104x96 mm with a height of 28 mm, the mouth is 

 sunken 12 mm below the test margin. The characteristic color is a yellow 

 brown with the petaloid areas and the lower surface dark brown in rather 

 marked contrast, but most of the specimens from Cocos (Nuez) Island, 

 Costa Rica, Panama and Ecuador are chocolate brown or purple brown of 

 a more or less deep shade, rarely, however, as deep as in speciosus. One 

 young specimen (48 x 44 mm) from James Island, Galapagos, in 10 fms 

 is red purple, rather dull above but quite bright orally. The smallest speci- 

 men (5 mm), also from James Island, is a uniform light brown while the 

 next largest (8 mm), from Ecuador, has the upper surface red violet. 



Distribution. — The most typical specimens are from Ecuador, 

 Colombia and the Secas Islands, Panama, but very good specimens are 

 from Albemarle Island in the Galapagos. A large number of Clypeasters 

 dredged at Nuez Island, ofT Cocos Island, in 31-50 fms are best referred 

 to this species although the only adult from this locality is very dark 

 colored. It has, however, the proportions and general appearance of ochrus. 

 No specimens of ochrus were taken north of Costa Rica. Records from 

 other authors extend the known distribution as far north as La Paz, Lower 

 California. 



Type.— M.C.Z. no. 4740. 



Type locality. — Acapulco, Mexico. 



Depth. — Shore to 50 fms. 



Specimens examined. — 47 specimens from 15 stations. 



