1906. 



NATURAL SCIENCES OF PHILADELPHIA. 



127 



Austin and San Antonio (Pilsbry, 1885); along the Guadalupe river, 

 three or four miles above New Braunfels (Ferriss and Pilsbry). Sing- 

 ley adds the localities Bastrop and Burleson counties. It is an Austro- 

 riparian species which reaches into the borders of the Lower Sonoran 

 area along the river bottoms. 



While the identity of Wood's H. sayi with auriforfnis is not estab- 

 lished with sufficient certainty to make a substitution advisable, in 

 our opinion, yet there can be no doubt that Wood had either that 

 species or one of its immediate allies. Helix sayi of Binney, 1840, 

 being a homonym, may be changed to Polygyra sayana {Terrestrial 

 Mollusks, III, pi. XXIII). 



Polygyra hippocrepis (Pfr.)- Figs. 3, 4. 



The known range of this curious snail is exceedingly restricted. It 

 has been found only near New Braunfels, in Comal county, Texas. 

 We found it in abundance in April, 1903, on the west side of the 

 Guadalupe river about four to six miles north of New Braunfels, 

 under stones near and at the foot of the bluff, with Holospira goldfussi. 

 Another place much nearer the town is on the rocky wooded hillside 

 above the springs of Comal creek, where we found a few living ones. 

 This place is just beyond the pleasure gardens. 



Fig. 4. 



The structm-e of the aperture of P. hippocrepis has never been fully 

 described or figured. The parietal tooth is not V-shaped as in other 

 PolygjTas, but U-shaped, hence the name hippocrepis — horseshoe. 

 There is an internal tubercle on the columella, as in P. mooreana. The 

 upper and lower lip-teeth enter and arch towards each other, forming 

 a U-shaped curve, which stands close to but a little deeper than that 

 formed by the parietal tooth. Where the two entering teeth join 

 there is a notch and a delicate slender hook with the point curved 

 towards the adjacent basal wall projecting forward. The immersion 

 of the originally lower lip-tooth gives room for a secondary callous 

 ridge along the basal lip, as shown in fig. 4. 



