00 MOLLUSCA. 



Trans, vol. vii. 175.) Now, to what does all this attention 

 of Linnaeus amount ? In all the species which he has de- 

 scribed, he has only noticed the animals of four of these, 

 and in a very slight manner ; and, with regard to the name 

 of the molluscous inhabitant which he included in his ge- 

 neric marks, we hesitate not to say, that by this union he 

 has betrayed carelessness. To many British ears these terms 

 may sound harsh, but the proof of their correct application 

 in the present instance will be abundantly evident, if we 

 examine the references to the animals of a few of his ge- 

 nera. The genus chiton is thus characterised ; " Animal 

 Doris. Testae plures, longitudinaliter gestae, dorso incum- 

 bentes." Are we not led to conclude from this character, 

 that the animals of the chiton exactly resemble the animals 

 of the doris genus, with the addition of the shells ? If this 

 be the case, how artificial is that system which places these 

 two genera in separate orders ! Upon turning, however, 

 to the genus doris among his vermes mollusca, we find the 

 following characters assigned to it ; " Corpus repens, ob- 

 longum, subtus planum. Os antice subtus. Anus postice, 

 supra cinctus ciliis. Tentacula duo, supra corpus antice 

 intra foramina retractilia." Now, the fine fringes around 

 the anus of the doris, which are the branchiae of the animal, 

 and form the essential character of the genus, are not to be 

 found in the animals of the chiton, whose branchiae are in 

 the form of leaves placed along the margin of the body, and 

 the anus is a simple pore. 



According to the generic character of the mya, the ani- 

 mal is an ascidia, with the appendage of a shell. Upon 

 turning to the genus ascidia, we find it said, " Corpus fix- 

 urn, teretiusculum, vaginans. Aperturae binae, ad summi- 

 tatem ; altera humiliore." To prove the impropriety of re- 



