292 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



test with 4 or 5 rather large ambulacral pores in each arc, and short, stout, 

 pointed primaiy spines of an almost black color. These spines tend to point 

 upward or definitely forward or backward and give the impression that 

 the urchins live in crevices or fissures in or between rocks. They do not 

 bore holes (as Echinostrephus does) but it is possible that they enlarge 

 crevices into which they fit themselves to some extent. Nearly all speci- 

 mens have the primary spines pointing more or less forward or backward, 

 parallel to the longer axis of the test. The largest specimen is 45 mm long 

 (not including spines), 39 mm wide and 29 mm high. If the spines are 

 included the corresponding measurements are roughly 80 x 55 x 40 mm. 

 The color of all the Velero specimens is uniformly very dark but not 

 black as one is inclined to think at first sight. It is rather a very deep purple, 

 as dark in the very young specimens as in the adults. Specimens of the 

 following species (VanBrunti) are often nearly as dark but the purple 

 tinge is more evident especially on the oral side. In the shape of the test, 

 this species is clearly more elongated and higher than the Panamic, and 

 the pore-pairs are definitely fewer, only 4 or 5, as against 6 to 8. Hence 

 there is no serious difficulty in identifying oblonga as it exists in the 

 Eastern Pacific. The trouble comes in the Western Pacific where the 

 ubiquitous mnthaei occurs so abundantly that it is difficult to draw any 

 definite line between some of its very dark forms and the similarly dark 

 oblonga. I think it must be agreed that oblonga is a variety gradually 

 differentiating into a quite distinct species and in the Eastern Pacific it 

 has attained that distinction. 



Distribution. — The Velero has found oblonga common at Sulphur 

 Bay, Clarion Island, and at Braithwaite Bay, Socorro Island. A fair-sized 

 adult was taken along shore at Bindloe Island, in the northern Galapagos 

 Islands. Along the western side of South Seymour Island, 7 very young 

 but quite typical oblonga were collected and at Cartago Bay, Albemarle 

 Island, an adult specimen was found. But not a single specimen has been 

 secured at Cocos Island or along the Mexican or Costa Rican coast. The 

 indications are that oblonga has come from the west and established itself 

 firmly at Clarion Island. From there it has spread to its near neighbor 

 Socorro, and from these two islands it is extending its range southward 

 into the Galapagos Islands but is not yet common there and has appar- 

 ently reached a southern limit at Albemarle Island. 



Type. — Unknown. 



Type locality. — Unknown. 



Depth. — Shore and vtry shallow water. 



Specimens examined. — 85 specimens from 12 stations. 



