912 Transactions of the Society. 



show no indication of the peculiar crest described, and differ also in 

 some other particulars. 



In conclusion, I may say that it seems to me most desirable 

 that minute, and even apparently trivial, features should be given in 

 the descriptions of species, and that when this is more done we may 

 find affinities between forms we should otherwise not suspect, and 

 be enabled by the examination of even an ambulacral tube or pedi- 

 cellaria, &c., to determine a species without the denudation of 

 portions of the corona, which is sometimes not desirable. 



