4() PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV, 
of the Chemung Schizophoria are represented in figs. 19, 17, and 18 
of the same plate, in which a shght septum extends forward. Fig. 
29 is drawn to express a depression along the center of the pedicle 
valve of a Dalmanella tioga. I have not seen such a form, and it is 
possible that the drawing at this point is erroneous. In all specimens 
hitherto examined by the writer, the V-shaped anterior termination 
of the median septum separating the muscular scars marks the 
Dalmanellas, and does not occur on specimens of Schizophoria. In - 
some specimens of Schizophoria there are seen two grooves continu- 
ing anteriorly, the inner edges of the muscular scars lying so close 
together as to form a thin median ridge,’ but in these cases the ridge 
is continuous with the median septum and does not divide into the 
V-shaped septum. The interpretation is that in such cases the double 
grooves are vascular markings which would not be likely to affect 
the exterior of the shell. The V-shaped forking of the median 
septum at the front end of the muscular scars in the pedicle valves 
is considered as a generic character separating the Devonian Dal- 
manellas from Schizophoria with which they are often associated. 
This character can be detected in some specimens in which the 
external carination is so slight as to be unrecognizable. 
A full statement of the authors’ interpretation of the characters 
of Dalmanella is given by Hall and Clarke ” in the work above cited, 
in which is given the following list of species representative of the 
genus there established (p. 207) : 
Orthis subequata Conrad.—Chazy fauna. 
Orthis testudinaria, O. emacerata, O. meeki, O. multisecta, etce.— 
Trenton and Hudson faunas. : 
Orthis elegantula.—Niagara. 
Orthis perelegans, O. concinna, O. plano-convexa, O. subcarinata.— 
Lower Helderberg. 
Orthis lenticularis Vanuxem, not Wahlenberg.—Corniferous. 
Orthis lepida Hall |not Schnur, H. S. W.|.—Hamilton. 
Orthis superstes, new species.—Chemung. 
To this list the authors add (p. 324) Orthis quadrans Hall from 
the lower Helderberg, and Orthis infera Calvin and O. leonensis Hall 
from the Chemung. 
Schuchert ¢ adds to the list: 
Orthis nettoana Rathbun.—Middle Devonian. 
In 1905, H. S. Williams @ called attention to the fact ‘het the species 
Orthis carinata and O. tioga of Hall, referred to the group Schizo- 
phoria by Hall and Clarke,’ properly belong to the group Dalmanella. 
“ As in the Plate XI, fig. 14, of Generic Illustrations of Brachiopods, Eleventh 
Ann. Rept. of the State Geologist for the year 1891. Albany, 1892. 
Oleml, ING Yeo, WILDL, 12th I, We, jo, SO—207. 
¢ Synopsis of Am. fossil Brachiopods, U. 8S. Geol. Surv. Bull. No. 87, 1897. 
@U. S. Geological Survey, Bull. No. 241, 1905, p. 3 
@ Ie, ING Mo, WIWKIE, IU, jo, P2XG, 
