122 AMERICAN JOURNAL 



acter applies only to certain species; but the genus is now 

 recognized by American naturalists to include all the species 

 with the columella thickened above and below. 



Prof. Haldeman's subgenus Angitrema is synonymous with, 

 and has pi'iority over, Glotella, Gray, both adopting Melania 

 armigera, Say, for their type. As this subgenus really 

 exhibits the highest development of the species, I have con- 

 cluded to adopt it as a genus, using Lithasia as a subgenus 

 for the smaller, smooth forms. 



4. Strephohasis^ Lea. 



5. Eurycselon, Lea. 



6. Go7iiohasis, Lea, May 1862. — This genus will retain Mr. 

 Lea's name. Potadoma, Swainson, as understood by M(;ssrs. 

 H. & A. Adams, embraces certain species only. These gentle- 

 men take some species of this. Strep! lohasis and Pleurocera, to 

 make their Megara, a subgenus of Gyrotoma [Schizostoma I) 



They make of the plicate group, 3IeJasma, and of the 

 striate species they form Juga. These names may be retained 

 as sections of the genus, possessing no reall}^ generic characters. 



7. Schizostoma^ Lea, Dec, 1842. — Messrs. Adams, Brot and 

 Anthony, adopt Gyrotoma, Shuttleworth, July 22, 1845, be- 

 cause Schizostoma was pre-occupied. 



Mr. Lea was himself of the same opinion, and changed the 

 name to Sell izocheilus ; (also pre-occupied.) He subsequently 

 reclaimed the original name, and I give him the genus as first 

 published, having two and one-half years' priority over 

 Shuttleworth. I entirely agree with Mr. Lea, that Aielaioma, 

 Swainson, represents an exotic, and not an American, group. 

 Mr. Anthony is ignorant how his name came to be used in 

 connection with Melatoma. It was first so used by Dr. Gray,* 

 (perhaps through inadvertance,) and afterwards by Mr. Reeve. 



8. Mesechiza, Lea. 



9. Anculosa, Say. — Leptoxis, Rafinesque, as already men- 

 tioned, is not described definitely enough to justify its substitu- 

 tion for Say's name. Prof. Haldeman, with the aid of Rafi- 

 nesque's MSS. work, identified the genus and used the name. 

 He has been followed by Messrs. Adams, Brot and Binney, 

 while Messrs. Lea, Conrad, Anthony and Reeve, have 

 adhered to the old name. I think that Elllpstoma, Raf., 

 (Jour, de Phys.,) really applies to this genus much better than 

 Leptoxis. and might be readily taken to represent such a form 

 of it as crassa, Hald. 



Prof. Haldeman proposed a subgenus Mudalia for certain 

 thin species without enamel on the labium, and probably 

 intended to include such globose forms as altilis, Lea, &c., but 



*Mr. Anthony never described such a shell as Melatoma altilis, Anth., 

 referred to by Dr. Gray. 



