100 PALEONTOLOGY OF IS^EW JEESEY. 



being only very slightly oblique, and with very ventricose valves. The other 

 is more elevated, less rotund, and very equilateral. There appears to have 

 been much uncertainty in the minds of most authors who have studied 

 these shells as to their specific identity and also as to their relations with 

 those from other localities. Dr Morton describes two species in his synop- 

 sis, from Prairie Bluff, Ala., and mentions a third species which he says 

 occurs in the ''marls of New Jersey." In Vol. V, p. 44, Am. Jour. Conch., 

 Mr. Conrad gives this last the name Axinea Mortoni, giving a figure but no 

 description. While Messrs. Gabb and Meek have considered the New Jer- 

 sey specimens as the same with those from Prairie Bluff, Ala., D'Orbigny 

 takes the name of one of Morton's Prairie Bluff species, P. australis, and sub- 

 stitutes a new name, P. subaustralis, for it, and cites New^ Jersey as the locahty 

 (Prod, de Pal., Vol. II, p. 24.5, No. 667 ). The Alabama specimens, of w liich I 

 have seen casts, are all small, but are broader in proportion to their height than 

 are those from New Jersey, while the beaks are sharper and have a decided 

 anterior incHnation. Considering all the above facts, I am inclined to con- 

 sider the New Jersey forms as distinct from either of the Alabama species, 

 and to adopt Mr. Conrad's name Axinea Mortoni for the smaller and more 

 rotund of the two species, that one corresponding most nearly with the 

 figure which he gave with the name. The shells are found of various sizes 

 up to an inch and an eighth in height, with a transverse diameter somewhat 

 greater, while the thickness of the united valves slightly exceeds three- 

 fourths of an inch. The form is nearly circular, slightly oblique, the valves 

 most ventricose on the umbonal region. Area ver}^ small, short, and nar- 

 row. Surface marked by concentric lines of grow^th, and rather even sub- 

 obsolete radiating striae. The internal casts, which I have identified as the 

 same, show the hinge plate to have been fairly wdde on the sides, and to 

 have been marked by eight or nine teeth on each side, as far as can be 

 seen outside of the breadth of the filling of the beak, wdiich are directed 

 very nearly or quite at right angles to the' line of the inner border of the 

 plate. Inner mai^gin of the cast strongly crenulate. 



The shell in its general form closely resembles A. rotundaia Gabb, 

 described from the Cretaceous beds at Eufaula, Ala., but is more ventri- 

 cose, more distinctly striate, has a rather smaller area, and possesses a little 



