1899.] 



NATURAL SCIENCES OF PHILADELPHIA. 



403 



NEW SPECIES AND VARIETIES OF MOLLUSKS FROM MIAMI. FLORIDA. 



BY HENRY A. PILSBRY. 



Bifidaria rhoadsi n. sp., figs. 1 aud 2. 



Shell rimate, very minute, cyliudrical, blunt at the ends, espe- 

 cially above, glossy brown, somewhat translucent ; obliquely, deli- 

 cately striated. Whorls nearly five, the third and fourth extremely 

 convex, the last less so, somewhat compressed laterall)' behind the 



lip, marked there with 



a slight furrow extend- 

 ing from the lip-edge 

 to about the position of 

 the upper palatal lam- 

 ella. Aperture round- 

 ed, truncate above, ob- 

 structed by five teeth 

 or lamellre : two upon 

 the parietal wall, one 

 slightly connected with 

 the right termination 

 of the lip, the other 

 more deeply placed ; columellar lamella strong, spirally enter- 

 ing, outer lip with two short lamellse. Peristome broadly ex- 

 panded, the outer lip somewhat incurved about the middle. Alt. 

 1.92, diam. 0.92 mm. 



Miami, Dade coimty, Florida. Collected by S. N. and ]M. C. 

 Rhoads, February, 1899. 



This very minute species is somewhat allied to certain forms of 

 ^Mexico, Xew Mexico and Arizona, remarkable for the partial or 

 complete separation of the two parietal lamellse, which in the ordi- 

 nary Bificlarke, such as conirada, rupicola or armifera, are united 

 to form a single bifid lamella. The disposition of the lamellae is 

 best shown by fig. 2, the shell being viewed obliquely from the 

 base. 



In this separation of the two parietal folds, B. rhoadd some- 



