NO. 1596. DALMANELLAS OF THE CHEMUNG—WILLIAMS. 61 
a broad sinus (see fig. 12). The radiate surface lines after the first 
stage of growth lose their fasciculated mode of growth and become 
fine and uniform over the surface, finer than on the surface of D. 
leonensis. ‘The cardinal process and crurae are close up to the hinge 
line and are not conspicuous on the inner walls of the shell. 
In the brachial valve the radiating, slightly elevated ridges bound- 
ing the muscular scars are dominant, other markings of the scars are 
inconspicuous. 
In the pedicle valve the muscular scar is bilobed, the central por- 
tion of the medial septum low but running forward, as in Schizo-. 
phoria, the diverging part of the septum is inconspicuous. 
The form of the pedicle valve is narrower at cardinal than at front 
end but it is not so wide anteriorly as is the brachial valve. 
The brachial valve shows a short hinge line and a gradual increase 
in width to near the front where it abruptly curves into the front 
margin (see fig. 16). The form of the pedicle valve is nearly flat 
about the beak, and scoops outward toward the antero-lateral angles 
as in typical Dalmanella carinata (see figs. 12 and 22). In size the 
species averages about 14 mm. long by 16 mm. wide; larger specimens 
reach the width of 17 mm. — 
One of the figures given by Hall in illustration of Orthis leonensis 4 
representing a brachial valve and another figure of a pedicle valve 
referred with doubt to Orthis thiemei White are both believed to 
belong to this species. 
Type specimens of Vhiemella villenova were found associated with 
D. leonensis in Dye’s quarry in the eastern part of the town of 
Villenova, Chautauqua County, western New York. They are fig- 
ured on Plate II. 
Fig. 16 (1225 Bt, specimen No. 31), mold of interior of brachial 
valve. 
Fig. 19 (1225 B*, specimen No. 35), mold of interior of brachial 
valve. 
Fig. 22 (1225 B*, specimen No. 46), mold of interior of pedicle 
valve. 
Fig. 23 (1225 Bt, specimen No. 55), mold of interior of pedicle 
Fig. 12 (1225 B*, specimen No. 103), mold of exterior of pedicle 
Fig. 11 (1225 B!, specimen No. 104), mold of exterior of brachial 
The specimens were collected by G. D. Harris for the U. S. Geo- 
logical Survey and will be deposited in the National Museum, Wash- 
ington, D. C. 
WIP BUI, ING Mos IDG Jets dls oll, We, ike, fy 
