EARLY DEVONIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA I 25 



median fold. The striae are sharply elevated, increase very rapidly by 

 implantation and on the cardinal slopes curve forward, out and back, in very 

 characteristic manner. Very tine concentric lines are visible in the intervals 

 between the striae. The dorsal valve is highly convex, the beak is not 

 prominent, the convexity is generally uniform with slightly depressed cardi- 

 nal slopes and sometimes a trace of a median groove. On the interior is a 

 strong bifid cardinal process and a short median septum. 

 Locality. Edmunds Hill. 



Dalmanella drevermanni Clarke 



Plate 31, figures 10-12, 1.1, 15 



Cf. Orthis tectiformis Walther. Neues. Jahrb. fiir Min. Beil. Bnd 17, 1903. p. 164, 



pi. 3, fig. 4 a-c 

 Orthis circularis Sow. mut. postuma Freeh. Lethaea Paleozoica. 1897. v. 2, 



pi. 24 1), fin. S. nam. 11 in/. 

 Orthis circularis Sow. D'Archiac & deVerneuil. Geol. Soc. Lond. Trans. 1842. 



v. 6, pi. 38, fig. 12 (11011 aiictoiinn) 

 Orthis subcarinata Hall. Palaeontology of New York. 1859. 3:169, pi. 12, fig. 



<~ 21 

 Dalmanella drevermanni Clarke. N. Y. State Mus. Bui. 107. 1907. p. 286 



This shell, the only one of its type in the fauna, is essentially a diminu- 

 tive expression of Orthis subcarinata Hall of the New Scotland 

 beds. It has affiliations, however, with other species, as cited above but the 

 conditions of its occurrence oblige us to regard the form as wholly mature ; 

 though with reference to others its expression is immature. The exteriors 

 of our shells indicate fine and somewhat unequal striation, with rapid multi- 

 plication of the sharp riblets, an almost flat dorsal valve with low broad 

 median depression and a medially elevated ventral valve with broad not 

 acute keel. It is closely similar to Orthis tectiformis Walther, as 

 cited, from the upper Coblentzian of the Haiger. 



Locality. Edmunds Hill. 



Orthis sp. 



Plate 31, figure 13 



Valves are present, but imperfectly retained, of a small Orthis having 

 an aspect quite unlike any species of the Appalachian province. 



Professor Kayser has called my attention to the close similarity of 

 expression in this shell and the Orthis personata Zeiler of the Siegen 

 greywacke. [See for illustration, Kayser. Beitr. zur Kenntn. d. Fauna d. 

 Siegen. Grauwacke : Jahrb. d. konigl. preuss. geol. Landesanst. 1892. 

 pi. 1 1-12] 



That is a uniformly larger species with rounder outline and I presume 

 when this Maine shell is better known it will prove a specific departure from 

 that somewhat peculiar orthid type. 



Loca/ity. Edmunds Hill. 



