INSTITUTE OF SCIENCE, PHILADELPHIA. 79 



of the body-whorl, giving the shell a less fusiform outline than in either 

 V. Floridana or V. Jiinonia* But just in this character the last two 

 species are absolutely in accord, yet, strikingly enough, the immature 

 shells of V. Trcnliolini and V. lUoridana are, in this respect, undis- 

 tinguishable. The fact that we have in the Miocene, Pliocene, and 

 recent periods but a single species of the type here referred to inhabiting 

 the (approximate) region under consideration, combined with the circum- 

 stance that over a considerable portion of this region no species of 

 Voluta are any longer to be found, lends, I believe, conclusive evidence 

 proving a case of true evolution and migration. 



Mitra lineolata, nov. sp. Fig. 9. 



Shell fusiform, gradually tapering ; spire elevated, of six or seven 

 volutions, terminating in a papillated apex, which, however, is wanting in 

 all but the youngest specimens ; whorls of spire deeply furrowed, three 

 pseudo-sulcations on each whorl, formed or bounded by four sharply 

 raised revolving lines or ridges, the lower of which is less prominent than 

 the others, and constitutes a supra-sutural carination ; suture slightly 

 impressed. 



Body-whorl gently convex, excavated below the suture, which is 

 bounded inferiorly by a double carination ; surface crossed by numerous 

 (nearly equally placed) elevated revolving lines, which are not raised into 

 ridges as on the other whorls ; towards the base these lines become 

 crowded, here and there appearing in pairs, which are separated by shallow 

 sulcations ; aperture semi-lunate, considerably more than half the length 

 of the shell ; outer lip thin. 



Columellar surface nearly straight, crossed by seven oblique plaits, 

 which rapidly diminish in prominence from above downwards. 



Length, four inches; width, 1.3 inches. 



Caloosahatchie, in the banks below Fort Thompson. 



This species most nearly resembles Mitra Carolinensis of Conrad, origi- 

 nally described from the Miocene of Duplin Co., North Carolina (Am. Journ. 

 Science, xxxix, p. 387 ; xli, p. 345, pi. ii.fig. 5),and subsequently identified by 

 Tuomey and Holmes from the nearly equivalent deposits of South Caro- 

 lina. The general characters of the two species are very nearly the same, 

 and on a cursory inspection the Florida and Carolina fossils could readily 

 be mistaken for one another. Closer examination, however, reveals the 

 following points of difference, which I find to be constant for all the 

 specimens of both species that I have had an opportunity to study : In 

 Mitra Carolinensis the revolving lines on the body-whorl are much less 



* The type specimen of this species, which has been kindly submitted to me for 

 examination by Prof. Whitfield, of the American Museum of Natural History of New 

 York, has a more markedly papillate apex than either the Florida fossil or Voluta Junonia. 



