minute, compared with the whole bulk of the animal, as to appear 

 quite rudimentary. The simple lateral uncini, moreover, are only 

 distinctly visible towards the posterior extremity of the sac. Both 

 these genera seem to be more intimately related to Murex and its 

 congeners than to the Buccinidce. 



Triphoris is now, as it would appear from the characters of its 

 shell alone, placed with Cerithium, but the comparison of the internal 

 anatomy of those genera offers no countenance to their supposed 

 affinity ; thus, single spherical otolithes occupy the auditory sacs 

 of Triphoris, while those of Cerithium contain otoconia. The pro- 

 boscis of the former is long and retractile. The lingual membrane of 

 Triphoris besides, though long and ribbon-like, supports a multiserial 

 pavement of minute teeth, while that of Cerithium is septiserial, resem- 

 bling in many particulars the tongue-strap of Pupina and allied forms. 



The Columbellte deserve to be elevated to the rank of a family, 

 distinguished from the Buccinidce by the unarmed rachis, and curved 

 versatile pleural teeth of the tongue-strap. 



Although not fully satisfied of the propriety of separating the 

 genus Conidea from Columbella, the author thinks there can be 

 no doubt that Pusiostoma, formerly placed with the Columbellce, 

 forms a very distinct genus clearly referable to the Buccinidce. 



As great difference "of opinion has always existed as to the distri- 

 bution of the sexes amongst Gasteropods, so far the author is unable 

 to vouch for the whole truth of the arrangement above given, but he 

 thinks that if there is anything incongruous in it, the correction of 

 errors in that particular would seem to be most likely to restore har- 

 mony and support the truth of the system. 



In the course of his inquiries the author was impressed with the 

 fact, that various genera of terrestrial gasteropods, which agree with 

 each other as far as regards their respiratory organs and mode of 

 respiration, differ essentially in their general organization, whereas 

 they are in this respect severally related to fluviatile and marine 

 genera, which are obviously constructed on the same anatomical type. 



In this way a terrestrial genus, having few structural points of 

 agreement to connect it laterally, as it were, with others of the same 

 habit, forms a member of a beautifully connected natural series, 

 traceable from it through fluviatile and littoral forms to others which 

 are altogether marine. 



