NO. 1596. DALMANELLAS OF THE CHEMUNG—WILLIAMS. 58 
The type specimens are from the quarry south of Cuba, Allegany 
County, New York, in the Chemung formation near the base; but 
the exact distance above the base is not ascertained. 
ORTHIS (DALMANELLA) SUPERSTES © Hall and Clarke, 1892. 
Plate II, figs. 26 and 27. 
The characters which distinguish this species from D. danbyi, 
the Devonian form of New York which is most closely resembles, 
are the following: In general form it is subquadrate, mflated, thick- 
shelled, but with surface markings much as in DP. danbyi. The 
exterior of brachial valves is marked by a “ shallow sinus from near 
beak to front which broadens toward the front.” In the pedicle 
valve, acording to the original description, “the beak 1s somewhat 
inflated and slopes evenly in all directions for nearly one-half of the 
shell; from this point forward is a broad low median sinus, which is 
most conspicuously developed in old and gibbous shells.” In this 
character the species differs from both D. leonensis and D. danbyi. 
_ The interior of the brachial valve has, besides the quadrate mus- 
cular markings, two pairs of vascular channels running obliquely 
from them ‘toward the margins; the first, or posterior pair, starts 
from the groove between the two scars of the same side and runs out 
obliquely toward the center of the lateral margin; the second set 
starts near the middle in front of the anterior scars and runs obliquely 
toward the antero-lateral corners of the shell. 
In the interior of pedicle valves, on each side of the middle of the 
shell, two faint vascular channels proceed forward from the front 
edge of the muscular scars and diverge shghtly from each other as 
they proceed; about halfway to the front each suddenly again 
divides into two smaller channels which diverge at nearly right 
angles from each other to near the front margin; the central branches 
nearly touch on the median line; the other two reach the front at 
about one-third distance from center to the antero-lateral angle of 
the shell. In Hall and Clarke’s figures there is also a central branch 
between the two lateral channels; this has not been detected in speci- 
mens in the U. 8S. Geological Survey collections. 
The above characters constitute the diagnostic marks by which 
this form is distinguished. The following specimens are selected 
as representative and are shown on Plate II: 
Fig. 27 (El. 3 I, E2 No. 11), mold of interior of brachial valve. 
Fig. 26 (Dr. 7 I, E2 No. 37), mold of interior of pedicle valve. 
Tpealities Kl. 3 I is directly east of Elmira, at base of hill ‘TIS: 
ing above oie northern bridge crossing Newtown Creek. 
OVA, ING Mo, WIU0 IP Is js ee Fok \ Wo, sie) Zu Lire Oneal a oncne from 
the Chemung group near Howard, Steuben County, New York. 
