XXX 



" The little shell which I now propose as a new genus, has 

 so distinct a character in the incision of the middle of the outer 

 lip, as to mark perfectly its place in the Melanidm of the United 

 States. It differs entirely in the character of the cut from that 

 in /ScJu'zostoma, which has, in all the many species I have seen, 

 a more or less deep incision immediately under the suture. 

 The living soft parts have not yet T3een observed. They maj', 

 when examined, prove to have some characteristics quite differ- 

 ent from Scliizostoma." 



Ein-ycadon. — In remarks on Goniobasis timbonata (Proc. 

 Acad., p. 3, Jan. 1864), " This is the fourth species of a natural 

 gi'onp which I haA'e described and which have a large ear-shaped 

 aperture. If they be not entitled to a generic place, they may 

 at least be considered a subgenus, for which I propose the 

 name of Uicri/ccelon, the aperture being larger than in the 

 Melanidm generally. All the species of Eurycwlon have a 

 callus on the collumella above, but not below, as in Lithasia, 

 and the base is more or less angular, which is not the case with 

 Anculosa. Those which we have considered as varieties of 

 Anculosa prcerosa, Say, which have an angular base, properly 

 belong, I think, to Euryccelon^ as well also Anthonyi, lledfield, 

 ficrbinata, and tintmnabulum (nobis), and some others. AVhen 

 the soft parts shall be examined, they will, I think, be found 

 to differ from Goniobasis, Trypanostoma and Lithasia, to which 

 genera they seem nearest allied. The operculum of the only 

 one I have seen is the same as Goniobasis, and the 3Ielanidce 

 generally." * 



Dr. James Lewis (Proc. Acad. Nat. Sciences, Dec, 

 1862, pp. 588-90) describes the soft parts of Jlela- 

 nia siibularis and Melania exilis, and remarks in 

 conclusion, that " the following features of the two 

 species above considered may suffice for placing 

 them apart in subgenera : — 



" 1. The presence of a sinus or fold in the sides of the foot 

 and neck of 3L siibidaris, and its absence in 3L exilis. 



" 2. The extension of the anastomosing black lines from the 

 margin of the lateral portious of the foot upwards along the 

 side of the neck in 3L subularis, and the restriction of these 

 lines to a narrow zone along the lateral oortions of the foot of 

 M. exilis. 



" 3. A well-defined dark band around the tentacle in 31. exilis, 

 not observable or at most only faintly indicated in 3L subularis." 



* Mr. Lea probably did not intend to include his tintinnahxdum in 

 Eiir>jcceloH, but did no inadvertently. I would add to tlie description 

 as jiiven above — shell generally obovate, longitudinally humped or 

 angled ; columella truncate below.. TLe genus may be placed between 

 the Lithasice and Gouiobaaes. 



