MIOCENE MOLLUSCA AND CRUSTACEA. 125 



features as obtained f'nun the casts by means ot gutta-percha* impressions 

 show a shell ot';il)oiit 1 inch in diameter, having- a height of a little more 

 than half an incii, and consisting of tlu'eo volutions, exclusive of the nuclear 

 apex. The upper luilf of the shell, counting the whorls, is smooth or with 

 growth lines, while the lower half is marked b\' oblique rows of foliated 

 spines, the rows folkiwing the growth lines, or parallel to the margin of the 

 aperture of the shell, and on the outer volution ai-e about an eighth of an 

 inch apart. The spines are hollow on the face and slightly recurved. The 

 volutions are moderately convex on the u})})er surface and the suture lines 

 distinct. On the under surface the volutions are rather distinctly concave, 

 the outer lij) strongly receding between the outer edge and the columella, 

 and being marked only by Hues of growth parallel to the margin of the 

 aperture. 



There can be no reasonable doubt of the proper identification of the 

 forms which show the surface marked with spines, with Conrad's figure of 

 T. perarmata in his Miocene fossils, but there might perhaps of the fragmen- 

 tary shells, chiefly the upper two volutions only, found in the sandy marls, 

 were it not for the imprints in the clays. When, however, the two are 

 examined together one is led to look for the spines of the larger ones on the 

 imperfect shells. On very many of them under a glass the bases of the 

 spines are quite readily observed, showing theu- relations to the imprints of 

 the more perfect ones in the clays. This leads one to the conclusion that 

 the specimens identified as T. centralis by Prof. Heilprin in his lists of the 

 fossils of the New Jersey Miocene, were only imperfect examples of this 

 shell, as no such specimen of T. ceiifralis has been observed in any of the 

 collections. 



Local if ies (iiid foniuitioi/ : In the grav sandy marls at Shiloh and Jericho; 

 in the stony layers at Bridgeton, and in the clays near Bridgeton, N. J. 

 From the collection at Rutgers College and the National Museum; the latter 

 collected by Mr. Frank Burus. 



