SECTION VI. 131 



Thofe recited authors who have ranged 

 them as Shells^ place them as Univalves, 

 or as Multivalves. The latter difpofition 

 is certainly very erroneous ; for, though 

 they define the many futures fcen in Echi- 

 ni as fo many valves, yet they cannot iil 

 any wife be reckoned as fueh, for they have 

 no play or niotion whatever, as valves, but 

 are meer joinings of feveral pieces, always 

 permanent and fixed. Neither indeed would 

 the name of Multivalves anfwer to all 

 Echini, could the futures even be termed 

 valves ; as only fome genera, not all Echi- 

 ni, are compofed of fuch futures. 



As for making them a genus of Mol- 

 lufca, with the Sea Stars, &.c. as Linnaeus 

 does, I can in no wife approve it 3 becaufe, 

 certainly, the Sea Stars being coriaceous, 

 and the Echini crufty, they demand dif- 

 ferent orders, for they cannot be reckoned 

 genera of the fame order. It is, therefore, 



K 2 1 thinjc 



