294: 



Notes on Lingual Dentition of Mollusca. 



In figure 11 outlines are given of one central tooth and the 

 three laterals of one side of the Ungual membrane, with [a and V) 

 the apices of two separate laterals, to show variation in the den- 

 ticulations. 



The generic characters of the animal of Tulotoma never having 

 been given, we add them here. Foot moderate, not produced 

 beyond the snout. Color dark blue. Head and snout small. 

 Lingual teeth as described above. Right tentacle broad. Left 

 cervical lappet small ; right larger, trough-shaped. Branchial 

 laminoe numerous, long, narrow, crowded in a double row. 



Fig. 12. 



Hesodoii leiicodon of Rafincsqiie. 



The name Mesodon leucodon, Raf., has found its way into the 

 books as a synonym of Helix ihyroides. As no description of any 

 such species was ever published by Rafinesque, 

 we have expressed the opinion that it was ori- 

 ginally a manuscript name sent by Rafinesque 

 to Ferussac. (IVrr. Moll. U. S., IV., 64.) 

 Since that time we have seen a manuscript 

 work by Rafinesque, entitled " Conchologia 

 Ohioensis," given by Prof. Haldeman to the 

 Smithsonian Institution. In this there occurs 

 not only a description, but a figxxvQO^ Mesodon 

 leucodon. These are here copied as concho- 

 logical curiosities. They have, of course, no 

 scientific value. 



Mesodon leucodon thyroide. " Mcsodon Lcucodon. Roussatrc, varic dc 

 petites taches brunes, irregulieres, provenantes de I'animal ; tres 

 finement strie entravers ; levre bordi aigu, reflechi ; dent blanche, 

 oblique au milieu de la bouche; forme bombee, convexe, obtuse; 

 opercule colle,membraneux." 



The operculum referred to is no doubt the epiphragm. 

 In the same manuscript are other figures scarcely recognizable, 

 but one of Mesodon labiatum^ a species not described in any 



