INSTITUTE OF SCIENCE, PHILADELPHIA. 279 



the others, become prominent and sharp, though not exactly nodulous. Alt. 

 of shell about 30; max. diam. 10 mm. 



I have elsewhere in this paper given my reasons for supposing the Jack- 

 sonboro' horizon to be early Miocene rather than Eocene, as supposed by 

 Lyell, yet in any case it lies close to the border-line between the two periods. 



Oeritlaiuin caloosaense Dall. 



Plate 15, figures 9, 11 ; var., 11 b. 



Cerithiiim ornaiissimum Heilprin, Trans. Wagn. Inst. i. p. 90, pi. 8, figs. 18, 18 a, 1887. Not 

 of Deshayes, M6m. Soc. G^ol. de France, t. 4, p. 320 ; t. 5, p. 41, pi. 17, f. 10, 1842, and 

 Pictet, Terr. Cret. de St. Croix, p. 290, pi. 71, f. 10, 1862. 



Pliocene of the Caloosahatchie beds and Shell Creek, Willcox. _ 



This fine species has two very minute nuclear whorls, which are nearly 

 smooth, followed by 23 slowly enlarging subsequent turns. It reaches a 

 length of 80 mm., with a maximum diameter of 2i mm. The slender 

 (? male) form measures 68 by 15.5 mm. It has the aperture of a Vertagjcs, but 

 is totally destitute of any ridge, groove or eminence on the pillar from the 

 beginning. Its characteristic features are (i) a fine, sharp grooving, covering 

 most of the shell ; (2) a thickened spiral band in front of the suture, especially 

 on the last whorl, followed by, counting forward, smaller primary, usually 

 nodulous bands grouped: 2, 3, thenagroove circumscribing the base, 2, i, i, 

 to the canal ; between the primaries are secondary rounded threads, merging 

 variably into the general striation, and frequently wavy ; (3) transverse, often 

 strong but obscurely defined waves to the number of about thirteen on the penul- 

 timate whorl ; these may be nearly obsolete ; they begin in front of the suture 

 and extend more than half way across the whorl. The nodulations on the 

 smaller primaries may be wavy, sharp and squarish, or rounded and beadlike ; 

 in the variety Heilprini (fig. 1 1 b) they are absent from the spire and few and 

 feeble on the last whorl. Until a large number are compared, the extremes 

 seem very distinct, but the gradations from one to the other form a continuous 

 series. The specimen of the variety figured is enlarged on the plate; it meas- 

 ures 40 mm. long (slightly decollated) and 1 1 mm. in diameter. 



This is one of the finest species known from our Tertiary, though there 

 is a form known chiefly by imperfect molds in the Ocala limestone that must 

 have nearly equalled it in beauty and size. 



The name proposed by Prof. Heilprin being preoccupied by a valid 

 species described from the Gault of France by Deshayes, I have supplied 

 another. 



Cerithium ocalanum n. s. 



From the Orbitoides limestone at Martin Station, Florida, in the form of 

 silicious pseudomorphs ; from the nummulitic limestone of Ocala, Florida, in 

 the form of molds, collected by Joseph Willcox, Esq. 



Shell large, pointed, many-whorled, somewhat distorted by numerous 



