262 PROCEEDINGS OF THE ACADEMY OF [Feb., 



of Lea, being shorter and relatively higher, and it is probably a true 

 Corbula. 



Under his description of Corbula aliforrnis {Am. Journ. Cone, II, 

 p. 76), Conrad remarks that "this shell belongs exclusively to the Shell 

 Bluff group and is very distinct from C. alia of the Mcksburg group." 

 This statement is difficult to comprehend as C. aliformis has been 

 found in abundance by Mr. C. W. Johnson in the bluff bordering Mint 

 Spring Bayou, at Vicksburg, at a point only a few feet removed in 

 elevation or horizontal distance from the pocket of sandy clay in 

 which I have taken the true C. alta plentifully. It is presumable, 

 therefore, that both these species existed contemporaneously in the 

 Lower Vicksburg. They are both completely unknown from the 

 Upper Vicksburg marl. There is no reason to suppose that other 

 species of this same subgenus of Corbula (Tiza De Greg.) may not exist 

 at Vicksburg, and in fact I have a single valve that seems to indicate 

 a third species, much more equilateral than the others. 



The small Mactra occurring in great abundance in the Lower Vicks- 

 burg is a different species from funerata, which occurs only in the 

 upper marl. It is probable that the former, which is much more 

 inequilateral, may be the one named imequilateralis by Meyer (Bull. 1, 

 Geol. Surv. Ala., p. 82), although the figure is rather poor. It is sin- 

 gular that the corresponding species occurring in the Jackson is the 

 counterpart of funerata from the Upper Vicksburg, and differs de- 

 cidedly from the Lower Vicksburg species. 



In the Conrad Catalogue {Am. Journ. Cone, 1865) there are two 

 species which appear to have been originally named Psamrnobia missis- 

 sippiensis, one under the genus Gari, on page 4, the other under the 

 genus Abra, on page 5; the references seem to show that they were 

 separately described and figured. The species Abra mississippiensis 

 is the only one of which I can find the type. It is broadly oval, but 

 slightly inequilateral and of moderately large size, relatively higher in 

 form than Abra perovata, with which it occurs very abundantly in 

 some parts of the Lower Vicksburg. The Gari mississippiensis {I.e., 

 p. 4) I cannot place and there appears to be no type in the Conrad 

 collection. 



There seems also . to be no type of Tellina perovata Conrad, 

 and I have not been able to identify this species from the material in 

 my cabinet. In the list referred to, the locahty "Claiborne" is 

 attached to this species, but probably in error. The Abra protexta of 

 Conrad, of which also no type can be found, is very abundant in the 

 Lower Vicksburg, to which it is entirely confined; but it is a Tellina 



