OP CONCHOLOGY. 53 



This species is introduced to show that a form very closely 

 allied to our own shells, inhabits a far-distant locality. Probably 

 the intermediate country of Mexico contains undiscovered species 

 exhibiting the same characteristics. The spire is represented 

 too much elevated in the figure. 



6. Triodopsis vultuosa, Gould. 



Plate 9, figure 14. 



Shell globosely depressed, closely delicately striate, rather 

 solid; spire convex, not much elevated, suture well impressed; 

 whorls 5|, convex, slowly increasing, the last subangular, and 

 deflected at the aperture, Avell rounded below, Avith a moderate 

 umbilicus ; aperture lunate, its outline somewhat sinuous, parietal 

 tooth a broad lamina, oblique, joined to the lip below, lower lip 

 tooth small, upper lip tooth expanded and reflexed. Dark horn 

 color. 



Diam. 10, height 5 mill. 



Texas. 



Intermediate between H. fallax and H. Texasiana. 



7. Triodopsis MuUani, Bland and Cooper. 



Plate 9, figure 15. 



Shell globosely depressed, irregularly striate, shining, with a 

 thin epidermis, covered with minute spiral lines and tubercles, 

 (the latter probably the scars of hairs) ; whorls 6, convex, much 

 constricted behind the aperture, and smoother on the base; 

 aperture trilobate, parietal tooth small, linguiform, lower lip 

 tooth lamelliform, upper one small, and sometimes obsolete ; um- 

 bilicus moderate, partially covered by the lip. Dark horn color. 



Diam. 13-5, height 7 mill. 



Washington Territory and Oregon. 



Darker in color, with smaller umbilicus and difi'erently formed 

 teeth from tridentata. 



