148 SHELLS AND SHELL-FISH. PART I- 



are the most important object to be illustrated ; while 

 the mere collector has no additional help to the no- 

 menclature of the specieSj more than he now has. 

 Long and procrastinated attention to these beautiful 

 shells, together with the invaluable delineations of their 

 animals by M. Quoy, has now enabled us to give the 

 following exposition of the genera and sub-genera.* 



Analogies and Characters of the Sub-genera o/" Con us 



and CoRONAxis. 



C0Nt;S. CORONAXIS. 



Shell not coronated. Shell coronated. 



C. litteratus. f Shell ponderous ; basal whorl not ^ nandanus 



Virgo. \ contracted near the suture; \ marmoreus 



generates. ( spire in general flattened. J 



striatus. f Shell ponderous ; basal whorl con- T jij-cnntus 

 stercus-mnscarum. < tracted near the suture; spire > cedo-nulli 



ammeralis. C short, pointed. j 



bullata. r Shell light; basal whorl ventri- i 



textile. 3 cose ; aperture eS'use ; the base { Tulina 



auratus. j hardly notched ; spire short, C 



aulicus. C pointed, concave. } 



nussatella. C Shell sub-conic, cylindrical, trans- 1 



glans. < versely grooved; spire elevated, >^sp^r? 



terebra. C thick, convex, generally obtuse, j 



amadis. f Shell conic, light, often trans- ^ 



gramiis ^ versely striated; spire concave f ^..„^ 



duplicatus. j elevated, and ponited ; outer ( 



australis. C lip deeply sinuated above. j 



This, perhaps, is one of the most remarkable instances 

 of analogy yet brought before the reader ; inasmuch as 

 the characters used as analogies are those only by which 

 the shells of each group, or sub-genus, of Conns and 

 Coronaxis, can be defined. Nothing additional, in fact, 

 can be added to separate, for instance, the sub-genus of 

 Conus, whose type is C. litteratus. from its represent- 

 ative, C. marmoratus, in the genus Coronaxis : so per- 

 fect are these resemblances, that we do not actually 

 know where the two groups join and unite. As to the 

 circularity of each, there cannot, we apprehend, be the 

 least doubt ; for the intervening shades of difference are 

 so gentle, that we hardly know where one type ends, 



* The names of the types are in Italic ; those of the annectant species in 

 Iloman. 



