MOLLUSCA. 151 



It consists of regularly pectinated plates. Its excretory ca- 

 nal terminates at the pulmonary cavity. 



The organs of generation consist, in the female parts, of 

 an ovarium, oviduct, and uterus ; and in the male, of a tes- 

 ticle, vas deferens, and penis, together with the peduncu- 

 lated vesicle ; and, as common to both the sexual organs, 

 there is a cavity opening externally, in which, by separate 

 orifices, the uterus, penis, and vesicle, terminate. 



As it would be impracticable to give, even in the most 

 condensed form, the characters of the numerous genera which 

 have been instituted, from our limited space, we shall rather 

 call the attention of the reader to the structure of a few of 

 the more remarkable genera. 



GENUS ARION. A mucous orifice at the termination of 

 the cloak. 



This genus was instituted by M. le Baron D'Audebard de 

 Ferussac, in his Histoire Naturelle Generale et Particuli- 

 ere des Moftusques Terrestres et Fluviatiles, folio, Paris, 

 1819> 3e. liv. p. 53. The species of which it consists were 

 formerly confounded with those which now constitute the 

 restricted genus Limax. It differs, however, in possessing 

 the mucous pore, in the pulmonary orifice being near the 

 anterior margin of the shield, with the sexual orifice under- 

 neath, and in the soft state of the calcareous matter, in the 

 shield. The author now quoted, has described four species, 

 and illustrated their characters by beautiful and expressive 

 figures. The Limax ater (together with its variety rufus) 

 of British writers may be regarded as the type of the genus. 

 The genus PI^ECTROPHORUS, distinguished by a conical 

 protuberant shell at the termination of the cloak, was like- 

 wise instituted by M. Ferussac, and nearly resembles the 

 preceding in form. Three species have been described 



