332 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 53. 



MELANELLA (BALCIS) GIBBA de Folin. 



Plate 43, fig. 2. 

 Eulima gibba De Folin, Les Meleagrinicoles, 1867, p. 64, pi. 6, fig. 4. 



"Shell imperforate, ventricose, acuminate posteriorly. The apex 

 rather obtuse, crj^stalline, very highly polished; whorls nine in num- 

 ber, increasing slowly in size, united by a simple suture. The final 

 whorl tumid, more strongly inflated toward the left. Aperture semi- 

 lunate. Margins simple ; columella strongly reflected. Long., 0.003; 

 diam., 0.0013. 



"Like the preceding, this species may also be considered remark- 

 able. It is corpulent, rather acuminate, recurved posteriorly, its 

 apex seeming to try to unite with the aperture. It is quite as diapha- 

 nous as adamantina and as highly pohshed. The spire is composed 

 of nine whorls. The early whorls increase slowly in diameter, but 

 proportionately they enlarge rather rapidly; the increase takes place 

 especially upon the left side. The final whorl, which alone consti- 

 tutes one-half of the entire shell, is very much developed on this 

 side. It is inflated and extends considerably beyond the fine, which, 

 judging from the margins of the preceding whorls, would serve as 

 contours for it. In order to recognize the aperture when the final 

 whorl has reached its maximum extension, it is necessary that it be 

 oriented toward the right following a very obhque line. These 

 abnormal conditions upon it, and consequently upon the entire sheU, 

 cause a hunchbacked outhne, which serves as one of the principal 

 diagnostics of this species. The suture is the same as that of E. ada- 

 mantina. The aperture is cordate, elongate; its margins are weU 

 joined, and are united by a curve which represents its greatest dia- 

 meter. The margins are somewhat thickened; the left, especially at 

 the base of the aperture, is reflected, and is expanded over the final 

 whorl in a decurrent angle, and at the same time it is reflected back- 

 wards over the columella. 



"Type locality. — Negritos; or Margarita Island, Panama." 



I have not seen specimens of this species and quote the description 

 and figure. 



MELANELLA (BALCIS) IOTA C. B. Adams. 



Plate 40, fig. 5. 

 Eulima iotaC. B. Adams, Ann. Lye. Nat. Hist. New York, vol. 5, 1852, p. 422. 



SheU very small, doubly flexed, seraitranslucent, polished. Early 

 whorls slightlj' rounded, the later ones flat, scarcely m.arked by lines 

 of growtli. Suture well marked. Periphery of the last whorl 

 obscurely angulated. Base short, well rounded. Aperture moder- 

 ately large; posterior angle acute; outer lip thin, inner lip fractured 

 (reconstructing from the preceding whorls, we may say that it is 

 concavely curved, reflected over and appressed to the base.) 



