ZOOLOGY OF THE BERMUDAS. 145 



This species, one of the gems among sea-urchins, is exceed- 

 ingly abundant in the flats about the North Rock. All the 

 individuals occupied recesses in the coral growth, which they 

 had by some means probably managed to keep open. It seems 

 hardly likely that they should have crept into these shelters 

 after they had been already formed, and that the association 

 is one of mere selection. 



The species is also abundant in the moderately deep water 

 that lies within the reef border. 



Hipponoe esculenta, Leske. 



North Rock, and the deeper water within the growing reef. 



Echinometra subangularis, Leske. 



Several specimens from the flats about the North Rock. 

 There is a certain amount of variation in the coloration of the 

 spines which ranges from olive or sea-green to purple. 



Toxopneustes variegatus, Lamk. 



We found this species very abundant in Harrington 

 Sound, where it rarely escaped being hauled up in our dredge. 

 It seems to frequent the calcareous bottom to a depth of 10-12 

 fathoms, or even more. Probably the species is equally abun- 

 dant elsewhere. 



Mellita sexforis, Agassiz. 



As before remarked, we did not ourselves obtain any speci- 

 mens of this species. It is said to be abundant along the cal- 

 careous bottoms of some of the inlets, as, for example, opposite 

 Flatts Village. 



