1906.] 



NATURAL SCIENCES OF PHILADELPHIA. 



167 



the whorls are rounded, the parietal laminse are as in Planorbula ex- 

 cept that the larger one stands more obliquely, the basal lamina i 

 transverse, but all the rest on the outer wall are entering plicce, the larger 

 lower one curving downward a little at its inner end, not upward as in 

 armigera and wheatleyi. As in all American forms of the genus only 

 one set of laminae seems to be present in any individual, though the 

 earliest set is formed at a very early age. In the European and 

 Asiatic species several sets are usuall}' present. 



PLEUROCERATID^. 

 Goniobasis comalensis Pilsbry. Figs. 24-28. 



Melania rufa Lea?, Romer, Texas, p. 457 ("In den Quellen des Comal- 



Spring bei New IBraunfels sehr haufig"). 

 Melania pleuristriata Say, A. G. Weatherby [Wetherby] American Naturalist, 



April, 1878, p. 254, with var. marmocki (springs of southwestern Texas)! 

 Goniobasis comalensis Pils., Nautilus, IV, p. 49, Sept., 1890 (Comal creek, 



New Braunfels). 

 G. 'pleuristriata Say and G. cornalensis Pils., Single/, Contrib. Nat. Hist. 



Texas, Geol. Surv. Tex. Ann. Rep., 1892, pp. 311, "312. 



Shell conic-turrite, thin but strong, covered with an olive-brown 

 cuticle. Whorls of the spire with a distinct keel which projects a 

 short distance above the suture, and is usually wanting on the last two 



Fig. 24. 



Fig. 25 



Fig. 27. 



Fig. 28. 



whorls; the whole surface showing fine sigmoid growth-striae, and in the 

 best specimens very faint, minute, spiral striae. Aperture ovate, the outer 

 lip thin, sigmoid, retracted below the upper insertion ; basal lip rounded 

 or subangular. Columella arcuate, somewhat thickened. Wliorls 

 about 7 in the most perfect shells, but usually fewer, the upper ones 

 being eroded. 



Length 18, diam. 7.3, aperture 7.3 mm. 



Comal creek at New Braunfels, Comal county, Texas. Also in the 



