334 PYRGINA. 



columellar or axial lamella in the last whorl, not visible from 

 the exterior, and a parietal lamella passing out beyond the 

 plane of the peristome. Length 15, diam. 4, aperture 2x2 

 mm. (Girard). 



Island of St. Thome at Binda, Morro de Gentio, Gumbella 

 and Bio Quija (F. Newton). 



Thomea newtoni GIRARD, t. e., p. 107, pi. 1, f. 16, 16a, 17 

 (shell), 18a, I (teeth). 



The embryonic young shells have a parietal lamella. In 

 the adult it is absorbed except in the last two whorls. 



Genus PYRGINA Greef. 



Pyrgina GREEF, Zool. Anzeiger, 1882, p. 518; Sitzungsber. 

 der Ges. Naturwiss. zu Marburg, 1884, p. 52. >GIRARD, Jornal, 

 etc., iii, p. 108 (1893). 



Shell dextral, cylindric, turriculate, composed of numer- 

 ous narrow, lightly striate whorls. Embryonic whorls ele- 

 vated in a point above the rest. Last whorl carinate at base. 

 Aperture oval, angular ; peristome simple and acute, the mar- 

 gins joined by a light callus. A parietal lamella visible at 

 the mouth, and a columellar fold within, not visible exter- 

 nally. Umbilicus round, open and deep (Girard). 



Soft anatomy unknown; but from its close resemblance to 

 Thomea there can be little doubt that Pyrgina also will prove 

 to be viviparous with a Stenogyroid dentition. The single 

 species is from St. Thome Island in the Gulf of Guinea. 



1. P. UMBILICATA Greef. PL 49, figs. 15, 16. 



Shell dextral, cylindric, turriculate, thin, covered with a 

 corneous-brown cuticle. Spire of 13 very narrow whorls. 

 3^/2 embryonic whorls form a projecting point above the fol- 

 lowing ones; the latter are slightly convex, parted by a well- 

 marked suture, and covered with slightly oblique, light, longi- 

 tudinal striae. Last whorl a little swollen, carinated at the 

 base around the umbilicus. Umbilicus rounded, very open, 

 prolonged in a grooved column. Aperture oval, a little an- 

 gular at the base, with thin, sharp margins. Columella 

 lightly reflexed, the margin joined by a light callus. There 

 is a columellar fold not visible outwardly, and a parietal 



