496 On the Echinidea of the f Porcupine ' Expeditions. [June 20, 



group it may be placed. The mouth is at the bottom of a deep anterior 

 groove, occupying the anterior ambulacral area. The arrangement of the 

 trivium is nearly normal ; but the bivial region is enormously prolonged 

 backward into a long rostrum, on the upper surface of which, near its 

 posterior extremity, the anus is situated in a pit partially covered by a pro- 

 jecting boss. The ambulacral pores are simple, one pore on each plate. 



1. P. Jeffrey si, n. sp. 



A single specimen of this very remarkable form was dredged in 610 

 fathoms to the north of the Sbetlands. It is nearly allied to P. miranda, 

 Pourtales, from the Strait of Florida, but differs in several details. 



2. P. phyale, n. sp. 



Two or three small specimens were dredged by Mr. Gwyn Jeffreys in the 

 Rockall Channel. All the specimens are immature ; but from the marked 

 difference in form, and from some other characters, I believe them to be 

 the young of a second species. 



Spatangim. 

 Brissopsis, Agassiz. 



1. B.lyrifera, Forbes, sp. 



Large specimens of this species are abundant from 50 to 250 fathoms. 

 Beyond the latter depth the specimens decrease in size, and at extreme 

 depths only examples which have all the appearance of being very young 

 are met with. These small delicate specimens were found at all depths, 

 even down to 2090 fathoms. 



Tripylus, Philippi. 



1. T.fragilis, D. & K. 



From 400 to 500 fathoms between Scotland and Fseroe. Hitherto 

 known as Scandinavian. 



Schizaster, Agassiz. 



1. S. canaliferus, Val. 

 A single small specimen from the coast of Spain. 



Amphidetus, Agassiz. 



1. A. ovatus, Leske, sp. 

 Abundant at moderate depths. 



Spatangus. 



1. S.purpureus, O. F. Miiller. 



2. S. Raschi, Loven. 



This species is apparently gregarious, and is enormously abundant in 

 patches here and there from the Faeroes to the Strait of Gibraltar at 

 depths from 100 to 300 fathoms. 



Of the twenty-sev^n species observed, six (namely Echinus Flemingii, Spha- 

 rechinus esculentus, Psammechinus miliaris, Echinocyamus angulatus, Am- 

 phidetus ovatus, and Spatangus purpureus) may be regarded as denizens 



