1903.J NATURAL SCIENCES OF PHILADELPHIA. 787 



Length 14.5; alt. 11, diam. 7.2 mm. 



liCngth 13.2, alt. 10, diam. 6.4 mm. 



Pond at Jalapa, State of Vera Cruz. Types No. 77,191, A. N. S. P., 

 collected b}^ S. N. Rhoads, 1899. 



This species is most nearly related to S. sulcatum (I.am.), ))ut it 

 differs in the following respects. S. jalapensis is more compressed and 

 greater in altitude ; it is more finely sculptured and more glossy. The 

 lateral teeth are less elevated. The outline of S. jalapensis is less 

 angular than that of S. rhomboideufn. S. luridiwi Martens, from the 

 State of Jalisco, is much smaller, about the size of a half-grown speci- 

 men of this species. The teeth are figured as very stout, but from the 

 description they would seem to be not very unlike those of S. jalapensis. 

 S. fabale is at once distinguished from all these species by its broad, 

 peculiarly compressed shape. 



In the specimen figured (PI. LII, figs. 1, la) the anterior lateral 

 teeth are reversed. In all others examined they are as described above. 



Sphaerium (Musculium) subtransversum Prime. PI. LIII, figs. 6, 6a, 66; I'l. LIV, fig. 5. 



Prime, Proc. Zool. Soc. Lond., 1860, p. 322; Monogr. Am. Corbiculidse, 

 p. 62; Sowerby, in Conch. Icon., XX, f. 38. Not S. subtransversum 

 Crosse and Fischer, Moll. Mex., II, 652. 



Tlalpam, State of Mexico; Morelia, Michoacan (Rhoads). 



This is an elongate, fragile species with distinctly " calyculate " beaks ; 

 gray, with a yellow zone below. The surface is shining and very finely 

 delicately striate. The upper and lower margins are about equally ar- 

 cuate, and the anterior end is more tapering than the wider posterior 

 end. The right valve has two diverging cardinal teeth and double 

 laterals (fig. 6a) ; the left valve has a single cardinal and single laterals. 

 The large specimen figured, from Tlalpam, measures: length 15, alt. 

 10.8, diam. 7.5 mm., but most of the lot are smaller, length about 

 11 mm. An average shell from Morelia measures: length 9.3, alt. 7, 

 diam. 4.2 mm. 



In my opinion the figures given by Crosse and Fischer do not repre- 

 sent this species. The dimensions given by Prime are: length .30, 

 alt. .20, diam. .10 inch. These must have been taken from a ciuite 

 young shell, but certainly it was lower and more compressed than 

 Crosse and Fischer's subtransversum, which ' measured : length 10.5, 

 alt. 8.5, diam. 6 mm. The figure given by Sowerby, while too small to 

 show any details, yet agrees with Prime's description in contour. 

 Sphaerium (Musculium) novoleonis n. sp. PI. LIII, figs. 5, 5a, 56; PI. LIV, fig. 6. 



Shell fragile, short and rather globose, the diameter slightly more 

 than half the length; thin; anterior end rounded, posterior end wider, 



