The IN'ew Species of Brachiopoda, 345 



.Orthothetes desideratus. 



Plate 5, figs. 1, 2. 

 Strepiorhynchus, sp.?Hall. Rept. State Geologist N. Y. for 1882, pi. (xi a> 



42, figs. 26, 27. 1883. 

 Orthotetes desideratus, Hall. Palaeontology of N. Y., vol. VIII, pt. l,p. 345, 



pi. ix a, figs. 26, 27. 1892. 



The original specimens of this species are internal casts of a 

 form with a subcircular marginal outline, very gibbous brachial 

 valve which has its greatest convexity central and slopes evenly 

 to the margins, though with a slight tendency to depression 

 toward the cardinal extremities ; a strongly and regularly con- 

 cave pedicle-valve, elevated at the beak and about the margins. 

 The cardinal area on this valve is moderately high and erect, the 

 hinge-line being slightly shorter than the greatest diameter of 

 the valves. The surface of both valves is covered with numer- 

 ous fine radiating striae. The general form and contour of the 

 species is very similar to that of Orthothetes umbraculum of the 

 Eifel. • 



Waverly group. Medina county, Ohio. 



Derbya ruginosa. 



Plate 5, figs. 12-14. 

 Derhya ruginosa, Hall. Palaeontology of N. Y., vol. VIII, pt. 1, p. 346, pi. 

 xia, figs. 25-27. 1892. 



Shell subelliptical in outline. Hinge-line short, its length" 

 being about two thirds the greatest diameter of the shell. Ped- 

 icle-valve shallow ; cardinal area moderately high, its lateral 

 slopes being slightly more than one-half the length of its base ; 

 apex scarcely prominent ; surface depressed or flat in the umbonal 

 region, becoming irregularly concave anteriorly. Entire valve 

 very irregular in growth, with conceatric ridges and furrows. 

 Brachial valve very convex ; apex depressed, but the umbonal 

 regioQ gibbous, the greatest convexity being reached at the cen- 

 ter of the valve. This valve is also of irregular growth, though 

 the irregularities are not so strongly developed as on the oppo- 

 site valve. The original specimen is an internal cast in chert to 

 which portions of the inner laminae of the shell adhere. There 

 are evidences of a flabellate muscular scar on the pedicle- valve 

 and a short ovate muscular area in the brachial valve. 

 44 



