210 Xe/c Sjiecics of Fossii>< fnini 01/ ia. 



Fonniifion (iiid Lui-aJihi. — In the clierty hiyers of the Upper 

 Ileklerberg liniestoue, near l)iil)]in. ami at Bellenarirf ([iiarry at 

 Goorgcsville, Franklin Co., Ohio. 



Gyroccra§ €uliiiiil>icii«e, n. sp. 



Pal. O., Vol. Ill, Plate (J, Fig. 8. 



Shell of about a medium .size, often attaining- a diameter acros.s the dise of 

 about six inches, although the majority of the specimens seen will not mea- 

 sure more than five. The shell is closely coiled, the volutions being in 

 absolute contact and about one and a half or two in mimber. Volutions 

 nearly circidar in a transverse section, being a very little greater in the lateral 

 direction than in the dorso-ventral, and the back of the volution barely 

 perceptibljr tiatteued on the outer jiortion of the larger one, but not perce[)- 

 tibly so on the inner portions. Septa deeply concave and distantly' arranged ; 

 the chambers measuring about half an inch each, on the outer two-thirds of 

 the body-volution of a specimen where the vertical, or largest, diameter of 

 the disc is five inches. Position of the siphuncle not absolutely determined. 

 Surface of the shell unknown. 



All the individuals of this species observed ure internal casts, 

 and occur in a rather rotten limestone, nnder conditions very 

 nnfavorable for the jn-eservatioji of the shelly substance ; conse- 

 quently the surface-characters have not been obsei'ved. It is an 

 abundant species, but owing to the conditions of preservation, 

 is not often found in collections. It will be readily distinguished 

 from the other described species by the closely coiled volutions 

 and the nearly circular section. It is perhaps more nearly ]-e- 

 lated to G. cyclops, Hall, IStli Eept. IN". Y. State Cab. Nat. 

 Hist., than to any other described species ; but it differs from 

 that one in its smaller size, and more rapidly increasing as well 

 as more closely coiled volutions, and does not appear to have 

 been provided with the broadly expanding and foliated varices 

 which, are so characteristic of that species. It might be objected, 

 that as the shell of this species is unknown, the determination 

 of the absence of these foliated expansions is not well authenti- 

 cated ; but it may be answered, that as the two species are asso- 

 ciated in the same layers in the quarries where they are both 

 rather common, if they were really one and the same, the shell 

 would be preserved on these as well as on the G. cyclops, and 

 the expansions readily detected. 



Formation and Locality. — In the limestones of the Upjier 



