176 PROCEEDINGS OF THE ACADEMY OF [April, 



The aperture is ovate, columella very little thickened, somewhat 

 sinuous. 



Length 2.6, diam. 0.65, length of aperture 0.6 mm.; 6f post- 

 embryonic whorls. 



Type No. 3027, A. N. S. P. 



The spire of the nuclear shell is rather high for a snail of this 

 section. 



Turbonilla (Nisiturris T) angustula n n. 



Turbonilla angusta Gabb, Trans. Am. Philos. Soc, XV, 1873, p. 225. Not 

 Chrysallida angusta Cpr. 1864. 



The embryonic whorls are lost, with one or more of the neanic. 

 Subsequent whorls have straight, rounded, slightly protractive ribs, 

 w^hich do not reach to the lower suture, the lower ends of the concave 

 intervals abruptly limited but rounded, and showing very faint 

 traces of spiral stria, in part obsolete. On the penult whorl there 

 are 18 ribs. The rounded base has growth-lines and faint spiral 

 lines. The upper whorls are convex, later ones flattened, the suture 

 rather deeply impressed. The columella is very feebly sinuous, 

 somewhat thickened. 



Length 5.7, diam. 1.35 mm.; 10 whorls remaining. 



Type No. 3025, A. N. S. P. 



G.bb's name has been previously used in the subgenus Pyrgi sous. 

 His statement that the shell is ''without any trace of spiral lines" is 

 inexact, since faint spirals may be seen under the compound micro- 

 scope, though not visible with an ordinary hand lens. 



Turbonilla (Nisiturris) aratibacillum n. sp. 



The shell is small r and more slender than T. angustula, with 

 sculpture of rounded, vertica ribs extending barely to the lower 

 suture of each whorl and the periphery of the last, the lower ends 

 of the smooth intervals not sharply defined. There are 13 ribs on 

 the penult whorl. Base smooth. Columella straight, with dilated 

 edge. 



Length 3.3, diam. 0.75 mm.; 9 post-embryonic whorls. 



Type No. 3036, A. N. S. P. 



The embryonic shell is not perfect, but seems to have been of the 

 bulimoid form. The shell is less slender than T. pertenuis. 



Turbonilla (Nisiturris) insititia n. sp. 



The shell is extremely slender, with embryonic shell of bulimoid 

 shape; subsequent whorls at first convex, becoming flattened in the 

 lower part, sculptured with strong, rounded vertical ribs not quite 



