INSTITUTE OF SCIENCE, PHILADELPHIA. 239 



Ilyanassa (Paranassa) isogramma n. s. 

 Plate 20, figure 16. 



Chesapeake Miocene of James River, Va., near Bellefield, Harris; and 

 of the Cape Fear River, near the Carolina Central R. R. station at Wilming- 

 tan, North Carolina, Clark ; Pliocene of the Waccamaw beds, South Carolina, 

 Johnson ; and at De Leon Springs, Florida, Wright. The last locality is a 

 little doubtful in age, but probably belongs to the Pliocene, at least in part. 



Shell elevated, moderately heavy, with about seven moderately rounded 

 whorls, a distinct suture and even, uniform spiral threading, crossed only by 

 fine lines of growth ; the interspaces are usually narrower than the threads 

 and are sometimes mere grooves, the threads are occasionally feeble ; body 

 whorl not greatly inflated, the base not constricted, the fasciole obscure and 

 the canal extremely short ; the outer lip slightly thickened, internally lirate, 

 with about eight short lirse ; Ion. of shell 24 ; max. diam. 14 mm. 



This form appears to be distinguished from /. arata by its closer and finer 

 spiral sculpture, more elevated spire, less inflated last whorl, and generally by 

 a somewhat pupiform outline. 



Subgenus Ilyanassa s. s. 



Ilyanassa irrorata Conrad. 



Buccinum obseletum Tuomey and Holmes, Pleioc. Foss. S. C. , p. 135, pi. 28, fig. 5, 



1S56. Not of Say. 

 Triiia irrorata Conr., Proc. Acad. Nat Sci. Phila. for 1862, p. 562. 

 Ilyanassa irrorata Conr., Am. Journ. Conch, iii. p. 263, pi. 19, fig. 10, 1S67. 



Pliocene of the Waccamaw beds. South Carolina, Holmes and Johnson. 



This species seems sufficiently distinguished from its descendant, the 

 /. obsoleta, by its much stronger sculpture, larger size and heavier, distinctly 

 granulated shell. It is, however, closely related to it. 



Ilyanassa granifera Conrad. 



Ilyanassa [Paranassa) granifera Conrad, Am. Journ. Conch, iii. p. 263, pi. 19, fig. 6, 

 1867. 



Chesapeake Miocene of Yorktown, Va., Harris; and of the Natural Well, 

 Duplin Co., North Carolina, Burns. 



This species is well distinguished from the preceding by its rather uni- 

 form rounded, close-set riblets and the sharp, undulated spiral ridges which 

 cross them. 



It does not belong to the group of Paranassa, but to Ilyanassa as re- 

 stricted. It is almost always a distinctly smaller and less elevated shell 

 than /. irrorata. 



Ilyanassa granifera var. sexdentata Con. 

 Buccinum sexdentattim Conr., Proc. Acad. Nat. Sci. i. p. 308; 1843. 

 Tritia sexdentata Conr., Proc. Acad. Nat. Sci. 1862, p. 562. 

 Paranassa sexdentata Conr., Am. Journ. Conch, iii. p. 262. 



