150 NEW UNIONID^, MELANID^, ETC., 



paper I named a fine Schizosioma after Dr. Showalter, which he sent to me as new ; 

 but I find that Mr. Anthony had very shortly before described the same shell under 

 the name of carinifera. Wishing very much that Dr. Showalter's name should be 

 permanent in a genus to which he has so much contributed in bringing so many new 

 species to light, I dedicate this fine species to him, as an acknowledgement of the debt 

 due to him by all students of Malacology. 



EuRYCffiLON UMBONATUM. PI. 2-3, fig. 64. 



Testa nodulata, subfusiformi, subcrassa, obsolete vittata, tenebrosooliva ; spira valde obtusa ; suturis 

 valde impressis ; anfractibus irregulariter umbqnatis, subsuturis tumidis, ultimo pergrandi ; apertura 

 pergrandi, subelliptica ; labro acuto, leviter sinuoso ; columella superne incrassata, inferne subsinuoso. 



Shell nodulous, subfusiform, rather thick, obscurely banded, dark olive ; spire very 

 obtuse; sutures very much impressed; whorls with irregular bosses, swollen below 

 the sutures, the last one very large; aperture very large, subelliptical ; outer lip 

 acute, slightly sinuous; columella thickened above and somewhat sinuous below. 



Goniohasis umhoiiata, Lea. Proc. Acad. Nat. Sci., 1864, p. 3. 



Hah. — Smith's Shoals, Cumberland River, East Tenn., Major S. S, Lyon, U. S. E. 



My cabinet. 

 Diam. -48, Length -80? inch. 



Remarks. — I received only two specimens of this interesting species, and neither 

 being perfect at the apex the number of whorls cannot be ascertained ; probably 

 there are not more than five. Both these specimens have two small obscure bands 

 on the inside of the upper part of the outer lip. One has dark brown marks inside 

 and is brown at the bottom of the columella. One is much darker on the outside 

 than the other. The large irregular nodes or bosses are three on the body whorl of 

 one specimen and five on the other ; they are placed on the shoulder of the whorls. 

 The aperture is nearly two-thirds the length of the shell. This is the fourth species 

 of a natural group which I have described, and which have a large ear-shaped 

 aperture, — viz. : Melania ( Goniohasis) hasalis, midas, gihherosa, and now umboruata. 

 If they be not entitled to a generic place, they may at least be considered a subgenus, 

 for which I propose the name o? Eurycoelon, from ^^fJ! amplus and Kuxn cavitas, the 

 aperture being larger than in the MelanidcB generally. All the species o£ Eiirycoelon 

 have a callus on the columella above, but not below, as in Idihasia, and the base is 

 more or less angular, which is not the case with Anculosa. Those which we have 

 considered varieties of Anculosa prcerosa, Say, which have an angular base, properly 

 belong, I think, to Eurycoelon, as well also Anthonyi, Redfield, turhinata and tintin- 

 nabulum, (nobis,) and perhaps some others. Wheii the soft parts of the four species 

 mentioned first shall be examined, they will, I think, be found to difler from Gonio- 



