INSTITUTE OF SCIENCE, PHILADELPHIA. Ill 



Very closely resembles Conns Haitcnsis of Sowerby, a Santo Domingo 

 fossil, from which it may be distinguished by its more regularly depressed 

 crown, and the character of its ornamentation. The latter species is so 

 variable, however, that not impossibly the Florida form may ultimately 

 prove to be only a variety, although in the extensive series of specimens 

 contained in the Gabb collection, illustrating Sowerby's species, I fail 

 to find anything which fully agrees with it. 



1 Pleurotoma ostrearum, Stearns. 



I identify with this species a small Pleurotoma which appears to 

 differ (?) from the living form only in having the costae more distantly 

 removed from one another, and possibly also a little more prominent. 

 It very closely resembles P. abitndans, of Conrad, from the Vicksburg 

 deposits of Mississippi. 



Cypraea tumulus, nov. sp. Fig. 49. 



Shell completely involute, inflated, very convex, the greatest elevation 

 being immediately back of the apex ; the dome abruptly truncated pos- 

 teriorly, sloping more gradually in the direction of the anterior extremity ; 

 aperture narrow, subcentral, slightly flexuous, directed obliquely over the 

 apex ; outer lip produced somewhat beyond the inner lip posteriorly, with 

 about twenty-five evenly placed dental plications ; columellar surface 

 flattened, the teeth less prominent; surface of shell covered with very fine 

 revolving lines, which, however (in the specimens before me), are only 

 visible in immediate proximity to the aperture; base gently convex. 



Length, 1.6 inch; width, one inch; greatest elevation, .9 inch. 



This species may be readily recognized by the marked elevation of 

 its dome, which is more pronounced than in the case of any other 

 American species of the genus, except C. splicer aides, Conr., from the 

 Vicksburg (Oligocene) beds, in which this character is still more empha- 

 sized. The latter species may be distinguished by its globose form, con- 

 tracted aperture, and the absence of revolving striae. 



Onisoia Domingensis, Sowerby (1850). 



Q. Journ. Geol. Soc. London, vi, p. 47, pi. 10, fig. 3. 



Gabb, "Santo Domingo," Trans. Am. Philos. Soc., xv, p. 223 (as Morum). 



A single individual, measuring .7 inch in length, in which the gran- 

 ules are largely wanting on the columellar surface, a condition which, 

 according to Sowerby, also characterizes the young of the Dominican 

 form. Mr. Gabb affirms that this species is " very different from Oniscia 

 harpnla, Conr., from the Vicksburg Eocene [Oligocene], although Mr. 

 Conrad has asserted their identity." I must admit, however, that an 

 examination of the type of Conrad's species, described in the Journal of 

 the Academy of Natural Sciences for 1848 (p. 119), inclines me to the 



