22 Cincinnati Societij of Xatural Histonj. 



uiiich the plates are attached is vemov'eil, the h)vver ends of the plates 

 are exposed; this side of the plates is provided with a slightly defined, 

 longitudinal furrow. 



Specimens of this species are usuall}- coated with iron, which effect- 

 ually destroys their minute characters. Fortunateh ', the author found 

 .some fragments that were entirel}' free of that troublesome substance, 

 and from these the details of the above description were obtained. 



Named in honor of the energetic collector, Mr. II. E. Dickhaut. 



Foi'mation and locality: the specimens were found in the shales of 

 the lower part of the Hudson River Group, at Covington. K\. Eleva- 

 tion, about one hundred and fifty feet above low water mark in the 

 Ohio River. 



Lepidolites elongatus, n. sp. (Plate VII., fig. 16). 



{^iy.—Klongatus, elongated.) 



This species differs from the type of the genus mainly in its differ- 

 ent form. The form of L. dickJwuti is sub-spherical, while that of the 

 species under consideration is sub-cj'lindrical, with the ends usually 

 somewhat truncated. The length is generalh' equal to about three 

 and a half times the diameter or transverse measurement. The speci- 

 mens are coated with iron, and for that reason I was unable to ascer- 

 tain whether the plates differ from those of the type species. Their 

 arrangement is very much the same. 



This species seems to have attained a larger size than L. dickhauti. 

 The largest S[)ecimen found, though defectiVe at both ends, in its flat- 

 tened condition is nearly two inches in length, by three-fourths of an 

 inch in width. 



Formation, locality and collectors: same as the last. 



Orthodesma subovale, n. sp. (Plate VII., fig, 18). 



[Ety.— <?(/&, somewhat; ovale, oval.] 



Shell exceedingly thin, moderntel}' elongate, subovate, the length 

 equal to twice oi- twice and nearly a half the greatest height; cardinal 

 and basal margins sub-parallel; cardinal line straight for one-half the 

 length of the shell posterior to the beaks, bej'ond which point it grad 

 ually curves downward to near the posterior extremity, which is rather 

 abruptly rounded or slightly truncate; anterior end short, equal to less 

 than one (ifth of the entii'c length of the shell, very slightl}' contracted 

 beneath the beaks, and more regularly rounded than the posterior 

 margin; beaks small and somewhat pointed. Surface of the valves 



