312 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



bladder, and by the size of the duct of the same, which for a small portion of 

 its course is considerably smaller than the bladder, and then suddenly enlarges 

 and gradually expands until it reaches the vagina ; in this particular the spe- 

 cies is more bike tridentata than fallax. 



""riodopsis Van Nostrandi, Bland. 



This species is in form and character of the aperture very nearly allied to 



introferens, but is more decidedly costate, more convex at the base, -with smaller 



umbilicus, and without the internal tubercle. It connects intro- 

 Fig. 206. 



ferens and vultuosa with, but is quite distinct from, fallax. 



The measurements of a specimen with &\ whorls are : greater 

 diameter 12^, lesser 11 mill.; height, 7 mill. Of a specimen 

 with 6 whorls, greater diameter 10, lesser 8 mill. ; height, 5 mill. 

 (Bland.) 

 Eelix Van Nostrandi, Bland, Ann. of Lye. of Nat. Hist, of N. Y., XI. 200 



(1875). 

 Probably a species of the Cumberland Subregion, though thus far only 

 noticed at Aiken, South Carolina, and Augusta, Georgia. 



Animal long, tail pointed ; dirty white, darker on head, eye-peduncles, and 

 tentacles. 



Jaw as usual in Triodoj)sis ; ribs 1 7. 



Lingual membrane (PI. VII. Fig. I) long and narrow. Teeth 24 — 1 — 24, 

 with 10 laterals The centrals have no distinct side cusps or cutting points, 

 but the latter are replaced by decided bulgings on the median cutting point. 

 The figure gives the central, with the first, tenth, eleventh, nineteenth, and 

 twenty-fourth teeth ; the last two are marginals. 



Genitalia (PI. XV. Fig. G) differing from those of tridentata, fallax, and 

 Hopetonensis by the swollen, elongated, oval genital bladder, and by its duct 

 equally swollen, excepting at the base of the bladder, where it is narrow. The 

 bladder with its duct appears like one long, swollen organ, with a median con- 

 struction. SLx individuals have these characters constant, but the difference is 

 slight as a specific character. 



Triodopsis vultuosa, Gould. 



Vol. III. PI. XL. a, Fig. 4. 



Shell umbilicated, orbicular, depressed, about equally convex on both sides, 

 rather solid, dark horn-color, delicately striated ; spire a low dome, composed 

 of about 5j whorls, which are moderately convex, and separated by a well- 

 defined suture, the exterior one somewhat angular at periphery ; beneath, well 

 rounded, and perforated by a deep umbilicus, about one fourth as broad as the 

 base ; aperture rather large, lunate ; peristome moderately reflexed, tortuous, 

 white, having at the base a small tooth, and at the centre a deeply seated, more 



