1919.] 



NATURAL SCIENCES OF PHILADELPHIA. 



219 



Vaginulus moreleti C. & F. 



Jocolo and Esmeralda Plantation, Rio Dulce, Guatemala (A. A. 

 Hinkley) . 



Physa solidissima n. sp. PI. XI, flg. 8. 



The shell is imperforate, subglobular with very short spire, very 

 thick and solid, composed of 4f whorls, the last one a little fuller 

 above, convexly tapering downwards. Aperture semicircular; outer 

 lip evenly arcuate, thick. Columella very heavy, with a low thick 

 fold or convexity in the middle. 



Length 8.2, diam. 6.3, length of aperture 6.9 mm. 



Guadalajara, Jalisco, Mexico (McConnell and Crawford). 



This is very unlike any American species I have seen, not only 

 by its extreme solidity, but also by the very short contour. The 

 surface is marked by a few growth-lines, but the minute sculpture, 

 if any, and the color, cannot be ascertained until fresh specimens 

 come to hand. 

 Planorbula obstructa (Morelet). 



In a reservoir four miles north of Guatemala City, Mr. Hinkley 

 took a large series of shells agreeing with the small typical form of 

 S. obstructa except in the absence of internal "teeth" in the great 

 majority of specimens, though a few show them. This form, which 

 may be called mutation anodonta, is analogous to S. dentiens var. 

 cmmaruni Morel. It measures 5 to 6 mm. in diameter and has only 

 4 whorls. There are also several other lots in the collection of the 

 Academy, from places between Guatemala and Panama. 



NERITILIA V. Martens. 



The shell is neritiniform, with smooth columellar margin. Oper- 

 culum with, on the calcareous internal face, a raised ledge along the 



3 ^9\ I ! ■x. i basal and colum- 



ellar edges, rising 

 in a point or 

 ''peg", but with- 

 out a distinct 

 "rib." Radula 

 with no central 

 tooth, three lat- 

 erals on each side, 

 the outer one, or 

 major lateral, 

 large, oblique, 



with serrate cusp. Uncini or marginal teeth are extremely numerous 

 with wide, short, serrate cusps. Genotype, N. rubida Pse. 



Fig. 7. — Teeth of Nerililia. A, lateral teeth of one side, 



with part of the first uncinus. B, the first uncinus lying 



flat, the cusps foreshortened. C, laterals of both sides 



with four uncini; 1, 2, 3, first, second and third 



or major laterals. 



