412 Dr. J. E. Gray on the Tongues of Mollusca. 



respiratory organs, and the structure of the tongue ; the latter 

 characters of the marine kinds being evidently taken from Dr. 

 Loven^s paper. He proposes to form the group of genera which 

 Dr. Loven named Trochina, into an order under the name of 

 Rhiphidoglossa, and divides the Pectinibranchous Mollusca, after 

 the above group has been abstracted, into three suborders, ac- 

 cording to the disposition of the teeth on the tongue, thus : — 



1. Tcenioglossa. Tongue band-like, with seven rows of teeth, 

 without a retractile proboscis. 



This suborder contains the first eight families of Gasteropods 

 in Loven's paper. 



2. Toxoglossa. Tongue with two rows of teeth often barbed 

 at the end. Equal to the Pleurotomacea and Conina, the eleventh 

 family of Loven. 



3. Prohoscidea, with a retractile proboscis and tongue with 

 only three rows of teeth. This group is equal to the ninth 

 {Buccinea and Muricina) and the tenth family [Volutacea) of 

 Loven. 



This division of the tongues into thi'ee kinds is very useful, to 

 abbreviate the technical descriptions of the families, but I fear 

 that it fails as a natural division of the families into groups. 

 First, for I cannot consider that a natural system which sepa- 

 rates the Strombida, Cyprceada and CoriocellidcE from the other 

 Zoophagous Mollusca, and places them in a different suborder 

 from the other zoophagous families. 



Secondly, the characters are not suificiently distinct ; for 

 example the zoophagous genera, Aporrhais, Strut hiolaria, Do- 

 lium and Coriocella, and the zoophagous tribes of Naticid/B, Ve- 

 lutinidce, which have seven rows of teeth, of the Tcenioglossa sub- 

 order, have a very long retractile proboscis, the character of the 

 Proboscidea. 



Thirdly, these suborders do not provide for the genera of 

 operculated ptenobranchous Mollusca, Scalaria and Tornatella, 

 and the peculiar floating genus lantKina, which have numerous 

 series of teeth on the tongue like the Pulmonobranchia and many 

 Nudibranchia and Potamobranchia (this kind of tongue may be 

 designated Ptenoglossa) ; or for the genera like Eulima which 

 have no teeth on the tongue. 



Since this paper appeared Dr. Troschel has continued his ob- 

 servations, and published descriptions and figures of the tongues 

 of several exotic genera of terrestrial Mollusca (as Bulima and 

 Nanina), (Wiegmann's Archiv, 1849, 225, t. 4), and of sundry 

 genera of marine Mollusca found on the coast of Peru (Wieg- 

 mann's Archiv, 18.52, 152). 



M. Oersted has figured and described the teeth of Sycotypus 



