ECHINOIDEA. I. 



181 



csculcntus var. tcnuispina (p. 162), and so it gets the name of Echinus tenuispinus n. sp. It is, as 



seen by Norman, closely allied to esculentus, with which it agrees in the most important characters: 



primary tubercle only on every other ambulacral plate, and spines on the bnccal plates; it is easily 



distinguished from the latter by having far fewer 



tubercles, among which the primary series are very 



distinct, and by its white colour -- csculentus seems 



always to keep the colour in spirit. I am decidedly of 



opinion that it must be regarded as an independent 



species, not only as a variety of esculentus. It differs 



considerably as to habitus from this species, among 



whose forms I know no specimens with which it may 



be confounded. What I, above (p. 162), have interpreted 



as var. tenuispinus, is a peculiar form with short, fine 



spines, but with the usual colour of the test (from the 



Faroe Islands); accordingly it is not identical with 



Norman's var. tenuispinus. 



Strongylocrntrotuss li-vidus (p. 165) is by S 1 u i t e r (371) 

 mentioned from Dogger Bank it is Sir. dr0bachiensis. 



Finally I shall call attention to the fact that no single regular Echinid belongs to the large 

 cold depth north of Iceland. The account of the geographical distribution must otherwise be put off 

 until the whole Echinid-material has been examined. 



Fig. 12. Echinus tenuispinus n. sp. Natural size. 

 (From a photograph.) 



