NATURAL SCIENCES OF PHILADELPHIA. 
5 
median septum a law ridge appearing a short distance from the beak, and 
disappearing toward the middle of the valve; vascular imprints sectoriform 
reaching half way to the midvalve, separated from the median septum by a 
faint ridge (occlusor apophysis ?) on each side. External surface of both 
valves with numerous concentric lamellar striae and innumerable little pits 
which give the impression a finely granular appearance; pits more scattered 
and deeper toward the • anterior margin. Internal surface (of dorsal valve) 
exhibiting concentric lines and innumerable raised points, apparently corres¬ 
ponding with the pits of the exterior. 
Length *82 (100); width 1*06(129); length of hinge-line *55(67); length of 
cardinal process *04 (5) ; depression of dorsal valve *04 (5). Depth of ventral 
valve *15, with a length of *76. Another dorsal valve has a width of 1*46 and a 
hinge-line 1*22 long. 
This anomalous species has more the form of an Orthis or Strophalosia than 
a Producta. But there is no positive proof of the existence of spines, and the 
somewhat doubtful existence of an area in either valve furnishes only unsatis¬ 
factory grounds for referring it to either genus. At the same time it is difficult 
to understand how the externally projecting cardinal processes of the dorsal 
valve could be used without a fissure (and area?) in the ventral valve in which 
they could move. In view of all the facts, I venture to refer the species with a 
query to Strophalosia. Should the reference prove correct, it will be, so far as 
1 know, the first identification of this genus in American rocks. 
CHONETES, Fischer. 
Chonetes multicosta, n. sp.—Shell of medium size or larger, semicircular, 
with the greatest width along the hinge-line. Ventral valve depressed-ventri- 
cose, more or less flattened toward the hinge extremities, with a barely per¬ 
ceptible mesial sinus reaching two-thirds the distance to the flattened incon¬ 
spicuous beak; spines two (possibly three) each side of the beak, nearly at 
right angles with the hinge-line, of medium length, rather stout, the first mid¬ 
way between the beak and cardinal extremity, the second midway between this 
and the same point; area extremely narrow. Dorsal valve shallow, concave, 
with a depressed mesial fold extending nearly to the beak; socket plates very 
divergent; occlusor scars forming a very small elleptic pit near the beak. Ex¬ 
ternal surface of each valve bearing 180-200 fine, subflexuous, radiating strise, 
which increase dichotomously at all distances from the beak, and sometimes 
also by implantation. Surface of cast rather remotely punctate. 
Length of hinge-line *82 (100) ; length of shell *50 (61); convexity of ven¬ 
tral valve *12 (14). In most specimens the last measure is relatively less. 
Ranges from the base of the yellow sandstones into the base of the Burling¬ 
ton limestone. Intermediate in size between C. Logani and C. Fisckeri of Nor¬ 
wood and Pratten. It possesses a greater number of radiating striae than C. 
lllinoiensis of Worthen. 
Chonetes Illinoiensis, Worthen, (Trans. St. Louis Acad. Nat. Sci., i. 571;) 
C. Logani, Hall, (Iowa Rep. p. 598, pi. xii. fig. 1, a-e and 2,) not C. Logani , Nor¬ 
wood and Pratten, (Jour. Acad. Nat. Sci. Philada., [2] iii., p. 30, pi. ii. fig. 12, 
a , 6 , c .) 
Some confusion seems to exist among the species of Chonetes just mentioned. 
C. Logani was described “from the middle portion of the mountain limestone 
series,” at Burlington, Iowa, and characterized as having “about 30 rugose 
ribs.” The figure agrees with the description. Prof. Hall subsequently 
described a species from the Burlington limestone, of Burlington and Quincy, 
which he referred to C. Logani 1 Nor. and Prat., though, among the characters, he 
assigns to it “ 100-120 or more fine rounded dichotomizing striae.” Still later, 
Mr. Worthen, conceiving this form to be specifically distinct, gaveitthe name of 
C. lllinoiensis , remarking that it “ is restricted to the crinoidal beds of the 
1868 .] 
