INSTITUTE OF SCIENCE, PHILADELPHIA. 



97 



many-whorled, strongly sculptured upper spire, after the nucleus, with some 

 seven ribbed whorls in an axial length of 20.0 mm., this cone having some- 

 times a base of 14.0 and a diameter in front of the nucleus of 1.3 mm. 



A more thorough investigation of the Eocene and later Mesozoic strata 

 will reveal the progenitors of this type of shell. I believe it most probable 

 that they are an offshoot from the early Volutidce, much like Lapparia, but 

 more persistent. All the American species have normally three plaits, which 

 on account of the great diameter of the pillar and the numerous whorls of 

 the shell are very horizontal. Sometimes a short supernumerary plait is de- 

 veloped in front of the normally anterior plication, but this is an inconstant 

 character. 



It would not be surprising if the alleged Tiirbinella scolymiLs of the Santo 

 Domingo Miocene, on more thorough inspection, should prove to be T. Wil- 

 soni or an allied form, possibly the next species. 



Turbinella polyg-onata Heilprin. 

 T. polygonata Heilprin, Trans. Wagner Inst. i. p. 108, pi. 15, fig. 43, 1887. 



Miocene silex-beds of Ballast Pt., Tampa Bay; lower bed and upper bed 

 at Alum Bluff on the Chattahoochee River, West Florida. 



This species was described by Prof Heilprin from a quite imperfect young 

 specimen, but I refer it to fragments from Alum Bluff which exhibit a flat or 

 even excavated space near the suture, bounded in front by a wavy keel set 

 with flattened, triangular nodules. In the adult the body-whorl is smooth 

 behind the canal, and the shell must reach a length of six or seven inches. 

 The pillar is as solid as in Vasiun, being nearly an inch in diameter in a mod- 

 erate-sized specimen. 



Turbinella chipolana n. s. 

 Plate 10, figure 7. 



Near Chipola River, West Florida, one mile south of Bailey's Ferry, Cal- 

 houn Co., Florida; on Ten-Mile Creek, a mile west from the ferry; also at the 

 corresponding horizon of the Lower Miocene (lower bed) at Alum Bluff. 



This form would at first sight be taken for a variety of T. WUsoiii with a 

 little shorter spire and more rounded whorls than that species, but a study of 

 a good series shows the following distinctive characters ; 



The last whorl is rounded and not with flattened sides and the keel at the 

 shoulder is obsolete; there is no presutural constriction or band; the whorls, 

 except in the earliest on two, are not appressed, but distinct or even partially 

 channelled ; the space of 20.0 mm. from the base of the larval shell forward 

 includes three and a half instead of seven whorls ; instead of seven or more 

 ribbed whorls there are but two or three ; instead of uniform strong spiral 

 threads as in T. Wilsoni, the spirals on the early whorls alternate coarse and 

 fine ; the whorls are gracefully rounded and not flattened ; the diameter of 

 the spire at the anterior end of the larval shell is 4.0 mm., instead of 1.3 mm.; 



