oTO Systematic Paleoxtology— Upper Devoxiax 



"Surface striated; stria; angular, often fasciculate, curving upwards 

 on the hinge-line. 



" . . . , the stria; are angular, and every second one in the upper ]iart 

 of the shell, and ever}- third or fourth one in the lower part of the shell, 

 are stronger and more prominent; concentric striae fine and closely 

 arranged. In the casts, the character of the stria; is tolerably well pre- 

 served in the fasciculate arrangement, and in the curving upward at the 

 sides and on the hinge-line; while on the margin, they are much more 

 strongly impressed than on the middle of the cast. When the cast is 

 presented in fine shale or shaly sandstone, the surface is minutely punc- 

 tate ; and the shell Avhen preserved has the same character. 



'•' The muscular impression in the dorsal valve is usually but faintly 

 defined in the casts, which preserve the impression of a strong cardinal 

 process bifid at the extremity. The socket plates are strong and widely 

 diverging, and the area is extremely narrow. In the cast of the ventral 

 valve the muscular impression is sulipentagonal, deeply Ijiloljcd Ix-low; the 

 bases of the divisions rounded, and the sides slightly indented. The 

 area is narrow, incurved in the middle, and extends aliout two-thirds 

 the width of the shell." Hall, 1867. 



A number of individuals observed have greatest width posterior to 

 middle of valve showing a modification towards the form D. carinaia. 



Length 20 mm.; width 27 mm. 



Occurrence. — Jennixgs Formation, Chemung Member. EUerslie, 

 Pennsylvania, 1316 abundant, 1474 abundant, 1508; west of McCool 

 about 1300 abundant. 



Collection. — Maryland Geological Survey. 



Dalimanella carinata (Hall) 

 Plate LII, Fig. 5 



Orthis carinata Hall, 1843, Geol. N. Y. Rept. 4th Dist., p. 267, fig. 1. 

 OrtMs carinata Hall, 1867, Pal. of N. Y., vol. iv, p. 58, pi. viii, figs. 30-32. 

 Schizophoria carinata Hall and Clarke, 1892, Pal. of N. Y., vol. viii, pt. i, 



pp. 213, 226, pi. vi, fig. 22. 

 Dalmanella carinata Williams, 1908, Proc. U. S. Nat. Mus., vol. xxxiv, p. 57, 



pi. iv, figs. 1, 2, 4, 6. 



