146 TRANSACTIONS OF THE WAGNER FREE 



intervarical nodes ; the web between the shoulder-spine and the suture is bent 

 forward; the spirals corresponding to the spines are very coarse, but not much 

 elevated, and become stronger anteriorly as the spines diminish in strength 

 and length. 



The variety unispiiiosa was collected by Rich at Mazatlan. It has a thick 

 varix, hardly webbed, with only one short, recurved spine, which is at the 

 shoulder; a much recurved canal; a subtriangular section; and, owing to the 

 absence of webbing and spines, appears especially slender. This is the form 

 which in my report on the Blake Gastropods (A, p. 203) was contrasted with 

 the typical E. caiidata. 



Lastly, at the head of the Gulf of California, near the estuary of the Colo- 

 rado River, is found, both recent and in the Post-Pliocene of the vicinity, a 

 variety which may be called liinata, in which the intervarical nodes are obso- 

 lete ; the whole surface nearly smooth ; there are but two or three varices in 

 all, and they are narrow and not prominent. This variety reaches a length of 

 40 and a width of 18.5 mm. 



I have gone into details with regard to these shells, which come from 

 another region than that of which this paper professes to treat, because it is 

 evident that all these forms may be traced to an original late Eocene or early 

 Miocene stock ; and until a clear understanding is had of the recent branches, 

 as far as known, the amount of divergency between the Miocene and the 

 recent species cannot well be estimated. 



The first suggestion of Eiipleiira of which I have been able to find traces 

 is offered by Conrad's Triton mississippiensis (Journ. Acad. Nat. Sci,, 2d ser., i, 

 p. 118, pi. II, fig. 42, not 41, as printed), from the Vicksburg Eocene. In the 

 Middle Miocene (upper bed) at Alum Bluff on the Chattahoochee River, 

 Florida, a few specimens of a genuine Miocene Etcplenra were collected by 

 Mr. Burns. The E. caiidata was referred by Conrad to the Miocene on the 

 testimony of Emmons, and Conrad's erroneous supposition that all Tuomey 

 and Holmes's Pliocene was really Miocene. My own impression is that the 

 Eupleuras from both the Carolinas will prove to be Pliocene. 



Eupleura miocenica n. s. 



Plate 12, figure 9. 



Shell of moderate size, six-whorled beside the (lost) nucleus; spiral sculpt- 

 ure of (on the last whorl about nine) large, feeble, revolving, flattened threads, 

 with much wider interspaces and a very fine, often obsolete, spiral striation 

 covering the surface ; transverse sculpture of about eight stout, not very 

 sharply defined, moderately elevated ribs, which begin at the shoulder and 

 extend over the whorl, disappearing near the canal ; the spirals overrun but 

 do not nodulate them ; the last whorl has two varices, thickened more prom- 

 inently than the ribs, but not sharp-edged or spiny except for a single blunt 

 point occasionally developed at the shoulder; the primary spirals exist on the 



