GASTEEOPODA OF THE MIDDLE GEEBJST MAELS. 175 



NATICID^. 



Fatica abyssina Morton. 



Plate XXI, Figs. 13, 13. 



(For synonyms and references, see page 123.) 



A single cast only of what appears to be this species comes from 

 the yellow limestone beds at Timber Creek, New Jersey. It is some- 

 what weathered and eroded, and is entirely a cast, but the general ex- 

 pression is so near that of the species as it occurs in the Lower Marls, 

 that I see no sufficient reason for separating it. The form is perhaps a 

 little less patulose, and the under side of the volution at the edge of the 

 umbilicus somewhat more rounded, while the umbilicus itself may be 

 somewhat smaller proportionally than in the normal form. In its de- 

 pressed form the cast might perhaps be as readily taken for an imperfect 

 specimen of Gyrodes petrosa, but the volution is rather more erect, less 

 flattened on the outer surface, and does not possess the flattening of the 

 upper surface bordering the suture, as in that shell. The specimen has 

 been figured and given on PI. xxi, that it may be the more readily iden- 

 tified should other specimens be found. 



Lunatia Halli Gabb. 

 Plate XXI, Figs. 10,11. 

 (For citations and synonomy, see ante page 130.) 



Several specimens of casts of this species have been obtained from the 

 yellow lime sands at Timber Creek, New Jersey, and are in the collection of 

 the Am. Mus. Nat. Hist, New York City. They present the usual features of 

 the species, being much more erect and less ventricose than casts of any 

 other species of the Naticidge known from the State. The casts are very 

 poor and roiigh on the surface, owing to the material of which they are 

 composed, but still they may be readily recognized. The umbilical open- 

 ing is small and the top of the volutions quite narrowly rounded, not show- 

 ing any flattening on the surface, as do many of those from the Lower Marls. 



