84 TRANSACTIONS OF THE WAGNER FREE 



Strombus Leidyi, nov. sp. Fig. n. 



Shell of the general habit of Stronibus accipitriinis, thick, ponderous, 

 and, barring the wing, oblong-fusiform, with an abruptly reflected base ; 

 spire elevated, somewhat less than one-half the length of the shell, and 

 consisting of from eight to ten volutions ; the whorls flattened, the upper 

 slightly nodose along their basal margins ; surface of the whorls orna- 

 mented with numerous elevated revolving lines, which alternate irregularly 

 in size from twelve to fifteen on the larger whorls and are crossed at 

 right angles by longitudinal faintly-waved creases or ridges, representing 

 lines of growth ; body-whorl slightly concave on the shoulder, and pro- 

 jected anteriorly into a symmetrically curved wing, which ascends to 

 about the middle of the penultimate whorl of the spire, and whose furthest 

 expansion corresponds approximately with the centre line of the shell ; 

 body-whorl faintly tuberculated on the shoulder, the seven or more 

 tubercles continued as so many distinct ridges extending about half-way 

 to the base, and showing a tendency in some specimens to develop into 

 true nodes ; surface of the shoulder covered with numerous slightly- 

 waved or crenulated concentric lines, which below the shoulder are re- 

 placed by broad regularly-placed bands (about fifteen or sixteen in 

 number, and measuring about five to the inch), which, more especially on 

 the expanded portion of the wing, can be clearly seen to be of a composite 

 nature ; wing very thick, thickest near the margin, and but faintly reflected ; 

 columellar surface covered with a thick deposit of callus, which extends 

 nearly to the posterior apex of the recurved base. 



Length of largest specimen, eight inches ; greatest width, five inches. 



Very abundant in the banks of the Caloosahatchie below Fort Thomp- 

 son, where it is found from the water-line to the base of the Venus canccl- 

 lata (Post-Pliocene) bed; I am not sure that we obtained any specimens 

 from the latter deposit, but, doubtless, the species is also found there. 

 Specimens despoiled of the wings have the form of Conorbis, and could 

 readily be mistaken for giant species of that genus, especially as there is 

 a slight sinual flexion in the lines of growth over the shoulder. 



This beautiful stromb, which I take pleasure in naming after the dis- 

 tinguished President of the Philadelphia Academy, has unquestionably its 

 nearest ally in the recent Strombus accipitriinis, Lam. (S. costatus, Gmelin), 

 of the West Indian seas. Indeed, its resemblance to certain varietal forms 

 of this species is so great, that in the absence of specimens for immediate 

 comparison the one might almost be mistaken for the other, and I feel 

 confident that in the recent form we have merely a derivative from the 

 fossil; in other words, that the fossil species is the direct or immediate 

 ancestor of the living one. This conclusion is supported, apart from the 

 general characters uniting the two species, and the circumstance that 

 .$. accipitrinus is the only form now living in the region, or elsewhere, 



