238 C. K. Bevchcr — Zeptmriisca, a new genus of 



shells, at others free from organic life, at times taking the form 

 of extensive oyster beds, at others having more marine charac- 

 teristics, containing Natica duplicata, Area transversa, Car- 

 dinal magnum, Beaten sp. ?, et als. 



Wells dug in the vicinity demonstrate the continuity of this 

 bed inland, and Hilgard* has noted its occurrence farther west- 

 ward. These wells reveal, too, a substratum of fetid black clay 

 containing cypress logs, what seems to be the remains of a sub- 

 merged cypress swamp. An interesting fact is that these same 

 fetid clays have been encountered in wells dug in the suburbs 

 of Mobile, but so far as the writer has been able to ascertain, 

 the shell bed has never been found so far north. 



Overlying these shell beds on Mon Louis Island and making 

 the surface soil through south Mobile County are series of 

 cross-bedded sands and loams usually very light colored and 

 devoid of clay or pebble beds. These beds are about fifteen 

 feet thick and are quite similar to the beds of sandy loam found 

 in the western part of the city of Mobile. McGee* has deter- 

 mined these last named loams as belonging to his Appomattox 

 group, and should his identification prove correct it would 

 change the age of the Appomattox to a more recent date than 

 he now seems to suppose. 



It establishes, however, a further extension inland than 

 that marked by the present coast line and a fluctuation in the 

 elevation of the floor of the Gulf in post-Tertiary times, which 

 fact is believed to have not been previously noted. 



Cincinnati, 0., June 30, 1890. 



Art. XXXII — On Leptamisca, a 7iew genus of Braohiopod 

 from the Lower Helderberg group • by Charles E. Beecher, 

 Ph.D. (With Plate IX.) 



The species which is here proposed as the type of a new 

 genus has long been considered as belonging to Leptmna, and 

 was thus described in 1859. f In general external appearance, 

 both forms agree very closely, but on careful examination, some 

 differences may be detected and a comparison of the internal 

 features reveals marked distinctions which cannot be included 

 within the limits of a single genus. 



The probability of a needed separation was significantly in- 

 dicated by Professor James Hall, in a reference to figures of 

 this species published in the Report of the State Geologist for 

 18824 where it was designated as Leptama f {sub-genus ?) con- 



* Agric. and Geol. of Miss., pp. 15-L-156, 1860. 



f Pal. N. Y\, vol. iii, p. 197, PI. XVJII, fig. 2, 1859. 



X Id. explanation of plate (xv), 46, figs. 30, 31, 1883. 



