32 NEW YORK STATE MUSEUM 



length of the end. Beaks anterior, subterminal, valve slightly excavated in 

 front beneath them, making the anterior extremity relatively narrow. The 

 umbonal ridge is obliquely curved and lies high on the valves making the 

 postumbonal slope narrow. 



The specimens of this shell are not common and it would seem the 

 width of the postumbonal slope and the position of the ridge are subject 

 to variation by compression. In forms where this postumbonal slope is 

 broader the shell approaches the Orthonota solenoides Sow., 1 of 

 which specimens are before us from the Upper Ludlow of Braclnor lane, 

 Kingston. The latter shell, however, is broader and more produced behind 

 and has a shorter and more oblique hinge line. 



Horizon. No. 13. 



Sphenotus ellsi Clarke 



Plate 4, figures 24-26 



Sphenotus ellsi Clarke. N. Y. State Mus. Bui. 107. 1907. p. 226 



Shell elongate, subrectangular, hinge line and lower margin parallel. 

 Beak at the anterior fourth of the hinge, anterior slope uncurved, anterior 

 margin broadly rounded. Umbones not elevated, flattened and divided by 

 a sinus or cincture which traverses the valves obliquely backward though 

 without greatly affecting the regularity of the basal margin. Umbonal 

 ridge sharply developed, not crested ; extending to the postlateral angle. 

 Postumbonal slope broad and concave, its outer edge constituting the entire 

 posterior margin of the valve which slopes forward to the hinge. This con- 

 cave area is traversed by an obscure radial ridge. Surface of the valves 

 covered with fine concentric striae in low and irregular undulations over the 

 shell body ; these however are absent on the posterior slopes where sharp 

 concentric lines alone are visible. Length about one third the hight. 



This species appears to be closely related to the Sangu in elites 

 decipiens McCoy 2 from the Upper Ludlow of Kendal and North and 

 South Wales. 



Species name. Dr R. W. Ells, Canadian Geologist. 



Horizon. Nos. 9, 11, 12, 13. 



Carydium Beushausen 



In his exhaustive and most helpful treatise on the Devonic pelecypods 

 of Germany the late Professor Beushausen introduced the above name for 

 a group of small shells, equivalve, inequilateral, with well defined adductor 

 scars and hinges constructed of a thickened hinge plate on which are two 



1 Murchison. Siluria. Ed. 3. pi. 23, fig. 9. 

 "British Paleozoic Fossils, p. 277, pi. n, fig. 24. 



