38 University of Michigan 



The jaw-plates and the radula (fig. 6) are ahnost identical 

 with those of A. Hagellata belizensis C. and F., as figured by 

 the authors (1890), although their figure of the jaw, in par- 

 ticular, appears slightly idealized. Especially noteworthy are 

 the small size and sharpness of the cusps of the central tooth 

 and the broad and markedly double base of the second lateral. 

 The latter is represented from a slightly different viewpoint 

 in C. and F."s figure of hclizensis. In a few of the central 

 teeth of the three specimens examined the first of the lateral 

 cusps was double, and in many the outer cusp was double, so 

 that in a few cases as many as 11 cusps were found on a 

 single tooth. A single inner lateral, in which the inner of the 

 two small, outer cusps w^as divided, was also noted, while 

 there was a quite constant tendency for a third cusp to be 

 differentiated from the cutting edge outside of the other two. 



Arnpnllaria flagellata, subspecies erogata Crosse and Fischer 

 (1890). — Thirty specimens. Ampullaria seems to have a 

 peculiar ability to mature at almost any size. In places where 

 the shells are abundant, specimens two centimeters in length 

 have been seen in copulation. This was also noted in a Vene- 

 zuelan species. These small shells may or may not assume 

 the adult characters, so that those that do have a thickened 

 peristome and a quite different shape from those that do not. 

 These small specimens are never markedly malleate, as the 

 malleation is not well developed except in the older shells. 



The shells from the smaller, more temporary pools, espe- 

 cially from those in the burnt-over areas (H, V, b), appear 

 never to reach a large size, and thus form a quite well-marked, 

 ecological subspecies, which appears to fit the description of 

 A. erogata Crosse and Fischer very well. A. cerasum Hanley 

 is not very different, and may be a similar form, perhaps of 

 another species. Examples of A. f. erogata measure: 



