368 DESCRIPTIONS OF NEW SPECIES OF FOSSILS 



upwards and outwards to the peripheral margin, and inside of which it falls into 

 the broad deep umbilicus. Mouth nearly round; inner lip slightly thickened. 



Diameter 1 mm. 



Its minute size, square form, and strong ribs sufficiently distinguish this shell 

 from its congeners. 



V. PENTAGONA, Gabb, PI. 41, fig. 68. 



Cyclostrema id., St. Domingo Memoir, Trans. Amer. Phil. Soc, v. 15, p. 



I figure this Santo Domingo species merely for comparison with the Costa 

 Rican forms. It has not yet been found outside of Santo Domingo, 



PARKERIA, N. Gen. 



Shell minute, in form like Rotella (Umbonium), but with the shell substance 

 vitreous and transparent or translucent like Vitrinella. Inner lip thickened, and 

 the umbilicus covered with a not vei7 heavy callus, as in Rotella. 



The peculiarities of this genus are that all the known species are of this minute 

 size. In shape all could go well into Rotella, but the vitreous shell structure for- 

 bids it. I have serious doubts as to the propriety of placing this genus next to 

 Vitrinella, despite the structure, and strongly suspect that when the animals shall 

 have been examined, it will be found to be more nearly allied to Rotella. Named 

 after my friend Mr. C. F. Parker, Curator of the Academy of Natural Sciences of 

 Philadelphia. 



■p. viTREA, Gabb, PI. 47, fig. 69. 

 Umbonium viireum, Gabb, Tr. Amer. Phil. Soc, v. 15, p. 



This species may be taken as the type of the genus. It has not yet been found 



outside of the Santo Domingo Miocene. 



P. DiAPHANA, d'Orb, sp. 



Botella diaphana, d'Orb, La Sagra., vol. 2, p. 62, PI. 10, f. 20-22. 



Another species of the new genus. Living on the coast of Cuba, and fossil in 

 Costa Rica. 



I think it is very probable that R. semi-striata, d'Orb., loc. cit., belongs to this 

 same genus, but know it only from the published figures. 



P. INCONSPICUA, Gabb, n. s., PI. 4:1, fig. TO. 



Shell very small, vitreous, translucent, laterally expanded; spire low, whorls 

 four, convex, tops slightly sloping; side of whorl round; base gently concave; 

 mouth nearly round, a little oblique; inner lip thickened, encrusting the body 

 whorl, but not expanded beyond the mouth, anteriorly it continues thick until it 



