NERITINA. 53 



Lives in same region as the preceding form, but is said to be con- 

 stantly distinguished by its constricted whorl. 



N. PEROTTETIANA, Recluz. PI. 17, fig. 77. 



Shell globose, striulate, black, unicolored, whorls scarcely three, 

 the last tinged at the suture ; aperture bluish white, columellar area 

 plane, narrow, middle of the margin obtusely denticulate. 



Diam. 9-11 mill. 



India, Ceylon, Pegut. 



N. tristis, Phil, is a synonym. 



N. COLUBER, Thorpe. PI. 17, fig. 78. 



Undescribed, and only a single figure published, showing the 

 back. It is yellowish green, with black zigzag markings, and (if 

 not enlarged) is 15 mill. diam. 



Ceylon. 



N. JAYAXA, Recluz. PI. 17, fig. 79. 



Thin, concentrically striulate, epidermis yellowish, with reticulate, 

 flexuously angulated lines, mixed with small white spots; suture 

 narrowly channeled ; inner lip maculated with black, aperture yel- 

 lowish. Diam. 6 mill. 



An undetermined species sent by Dr. Jay of N. York to Recluz, 

 and therefore doubtfully ascribed to North America. I believe 

 that no one has recognized it ; it almost certainly is an old-world 

 species. 



N. SHOWALTERII, Lea. PI. 17, figs. 81, 82. 



Smooth, diaphanous, yellowish corneous, whorls 3, rapidly in- 

 creasing, suture inconspicuous, last whorl somewhat inflated, aper- 

 ture bluish white, edentulate, peristome continuous, forming a pos- 

 terior raised margin which limits the rather wide columellar area, 

 area smooth, slightly concave. Diam. 5'5 mill. 



Coosa River, Alabama. 



Several specimens were obtained, all without the operculum. It 

 has been suggested that this is a young Anculosa, but it has not 

 the characters of that group ; on the contrary, it more nearly ap- 

 proaches in general Neritina crepidularia. The coloring of the 

 epidermis more nearly resembles Anculosa however, than the other 

 fluviatile species of Neritina. 



