94 MOLLUSCA. 



' In the course of our review of the Linnaean genera of 

 bivalves, we have exposed some of those errors which the 

 Swedish naturalist committed in associating discordant spe- 

 cies under the same genus. Perhaps our examination of 

 the univalves will make us better acquainted with the im- 

 perfections of that system, and dispose us to prize those im- 

 provements which subsequent naturalists have introduced. 



18. ARGONAUTA. This genus, which contains but few 

 species, is highly prised by collectors, who call the princi- 

 pal species by the name of paper nautilus. By restricting 

 the characters of this genus, so as to embrace only those 

 species in which the opening is interrupted by the involu- 

 tion of the spire, and in which the dorsal ridge is double, 

 Lamark has been able to form the genus CARINARIA. In 

 tli is the mouth is entire, and the dorsal ridge single. It is 

 represented by the argonauta v.itrea of Gmelin. 



1 8. NAUTILUS. Since the days of Linnaeus, our know- 

 ledge of the multilocular testacea has been greatly enlarg- 

 ed. He contented himself with arranging all the species 

 with which he was acquainted under one genus, but, in con- 

 sequence of modern industry, even the genera exceed the 

 number of Linnaean species. Many recent species have 

 been discovered by the aid of the microscope, among the 

 sand on the sea shore, and a still greater number in a fossil 

 state among the calcerous strata. These newly discovered 

 kinds exhibit many different characters, and have compell- 

 ed conchologists to institute so many new genera for their 

 reception, that the genus Nautilus of Linnaeus appears rather 

 as the head of a family or order, than as a separate genus 

 of univalve shells. In this department the names of Bru- 

 guiere, Lamark, Montfort, Parkinson, and Sowerby, deserve 

 respectful notice ; and it is from their writings that the fol- 



