512 HISTORY OF COiXCIIOLOGY. 



At a season when " Systems " were all in vogue, Adanson, 

 with characteristic boldness,^leclared himself their enemy as 

 being worse than useless, fit only to amuse triflers, certain 

 to lead to error and alienate us from true views of the ob- 

 jects in question, and so easy of invention to boot that 

 several equally good might be made by one of common 

 experience and capacity. The history of conchology had 

 already offered too many examples of the truth of this as- 

 sertion, and he was not slack to give additional specimens in 

 its illustration. But notwithstanding his philippic against 

 them, Adanson, in some measure, forgot his own principles, 

 and was little less of a systematist than those were whom he 

 censured. Shell-fish were, according to him, distinguishable 

 in the first place into ' Limacons ' and ' Conques ; ' the former 

 were subdivided into univalves and operculated univalves, 

 and the Conques into bivalves and multivalves ; these pri- 

 mary families were still further divided into smaller groups 

 from the position of the eyes in the Limacons, and from the 

 figure of the respiratory tubes in the Conques. Now it was 

 a pure arbitrariness in him to fix upon the operculum as a 

 part or organ of primary value, for there is nothing in its use 

 or position to justify the choice, nor did he attempt, by any 

 analysis, to show that it was a regulator of structure and 

 habits ; and it was equally arbitrary to divide the bivalves 

 into two sections on the mere existence of a few additional 

 pieces over the hinge, for these pieces were not proved to be 

 an index to the animal's economy. But Adanson's services 

 to conchology are very great, — of those its labourers who 

 have passed in review we place him next to Lister. He has 

 the merit of having altogether removed from the Testacea 

 the Lepas and Balani, whose structure he saw was modelled 

 after the type of another category ; his interesting discovery 

 of the Vermetus was a fine illustration of the shell being of 

 itself useless as a character in natural history ; and his know- 

 ledge of affinities was made evident by the acuteness which 

 led him to approximate the Teredo to the Pholas. If not 

 the first to point out the importance of the operculum, he 

 was undoubtedly the first who knew its value as an index to 

 natural relationship between genera ; perhaps the first who 

 was fully aware that the entireness or canaliculate formation 

 of the aperture of the shell gave an insight into the habits 

 of the snail in regard to food ; the first too to point out fully 

 the influence of age and sex in altering the shape of the 

 shell, and more especially of its aperture ; the first to de- 

 scribe and delineate the animal tenant of many genera ; and 

 although his attention was exclusively directed to external 



