56 PROCEEDINGS OF THE NATIONAL MUSEUM. VOU. XXXIV. 
is the prevailing form in the upper half of the Cayuta member, and 
this typical form, )). toga, is rare above the middle. 
Specimens from the Survey collections selected to represent this 
species are figured on Plate ITI. 
Fig. 7 (El. 2K, In. No. 11), mold of interior brachial valve. 
Fig. 4 (El. 6C, B6. No. 8), mold of exterior pedicle valve. 
Fig. 10 (HI. 7J, 1c. No. 1), mold of interior brachial valve. 
Fig. 1 (EI. 7J, 1c. No. 3), mold of exterior brachial valve. 
Fig. 3 (El. 7J, 1c. No. 5), mold of exterior pedicle valve (dis- 
torted). 
Vig. 12 (El. (J, 1c. No. 2), mold of interior pedicle valve. 
The localities represented above are: 
El. 2K.—Elmira town, above Delaware, Lackawanna and West- 
ern Railroad, on east side of river about a mile north of Big Island. 
El. 6C.—Catlin, about one and a half miles south of Pine Valley 
at base of hill west of Northern Central Railroad track. 
El. 7J.—Section from Fitch bridge up ravine southeast side of 
Hawley Hill, a few miles west of Elmira. 
1455, Btt—Granville Center, Bradford County, Pennsylvania. 
DALMANELLA ELMIRA, new species. 
Mews JOOG, ess Gy tS, IG, les, IIa, GS 1G, ILA 
(= Orthis tioga Hatt (in part), as represented by figs. 21, 26, 27, and 28 on 
IP WIDE, JERI IN, 3%, JAY IU.) 
This species differs from QO. toga, as restricted, by its subquadrate ~ 
form; the length is from four-fifths to five-sixths the width. In the 
smaller as well as earlier specimens the greatest width is nearly 
medial, in specimens from the middle and upper Cayuta member the 
greatest width is in the upper third of the shell. | 
The typical surface form is low convex for the brachial valve, and 
nearly flat, but not concave for the pedicle valve. In molds of the 
pedicle valve the muscular scars are convex on their outer faces. 
The shell is convex along the line running through the middle from 
beak to front; it is flat or shghtly concave in typical specimens of 
D. carinata. | 
The typical PD. elmira is found associated with DP. téoga in the 
lower part of the Chemung, but in the middle and upper part of the 
Cayuta member 2). elmira becomes the prevailing species. 
Type specimens of Dalmanella elmira are figured on Plate IIT as 
follows: | 
Fig 13 (El. 6C, B6, No. 2), mold of interior brachial valve. 
Fig. 11 (El. 6C, B6, No. 3), mold of interior brachial valve. 
Fig. 15 (El. 6C, B6, No. 5), mold of interior pedicle valve. 
