244 SYSTEMATIC PALEONTOLOGY 



as 3 is to 4. mm., that is, the length is 18 mm. and the breadth 24 mm. 

 Other specimens from the same area attain as great a breadth as 35 mm. 

 The Vermont specimens are even more robust, an average specimen here 

 being 30 mm. long and almost 40 mm. broad. The arrangement of the 

 plications in bundles, each bundle being marked off by a stronger plica- 

 tion, is also a striking specific feature. The specific name is in honor of 

 the late George E. Edson, who discovered the species in the Trenton 

 rocks of Vermont. 



Occurrence. MARTINSBURG SHALE (Sinuites bed). Two miles south 

 of St. Thomas, Pennsylvania. Lower Trenton at Highgate Springs, Ver- 

 mont. 



Collection. U. S. National Museum. 



DALMANELLA MULTISECTA (Meek) 

 Plate LIV, Figs. 5, G 



Orthis emacerata var. multisecta (James MSS.) Meek, 1873, Pal. Ohio, vol. i, 



p. 112, pi. viii, fig. 3. 

 Orthis emacerata var. multisecta Miller, 1875, Cincinnati Quart. Jour. Sci., 



vol. ii, p. 22. 

 Orthis multisecta Sardeson, 1897, American Geologist, vol. xix, p. 97, pi. iv, 



figs. 20-23. 

 Dalmanella testudinaria var. multisecta Cumings, 1908, 32d Ann. Rept. 



Dept. Geol. and Nat. Res. Indiana, p. 901, pi. xxxiii, figs. 4, 4c. 



Description. " Shell small, subcircular, plano-convex, or sometimes 

 concavo-convex, hinge line shorter than the greatest breadth of the valves ; 

 valves thin. Dorsal valve nearly flat, or having a concentric depression 

 through the middle; mesial sinus undefined or indistinct; beak, small, 

 not incurved; area low at the middle, and narrowing off to nothing at 

 the lateral extremities; foramen very small and filled by the cardinal 

 process. Interior flat ; mesial ridge extending to about the middle of the 

 shell, without any well-defined termination; scars of posterior pair of 

 adductor muscles a little smaller than the anterior pair, from which they 

 are separated by a very fine line, or, more generally, not distinctly sepa- 

 rated; cardinal process very small, conical, obscurely trifid on the pos- 



