OF NORTH AMERICA. 
45 
Explanation of figures. — Plate VII , iig. 6. Side view of a specimen without the beak or the cardinal border. 
» VII, fig. 6 a. Side view of the beak. 
PRODUCTUS DELAWARII n. sp. 
Plate V. fig. 3. 
Description. — This species is related to the Productus Cora ; it has a pointed beak ; hinge line short , folded , with 
three or four rounded wrinkles , that become rapidly effaced before reaching the front , across which only very faint 
interrupted waves of growth may he occasionally seen. Surface covered with slightly flexuous , regular , narrow , 
thread like striae; intervening sulci deep, much narrower than the striae. The tubes and tubercles are rare and 
very small. 
Observations. — Related to the Pr. Cora-, but its hinge line is longer and its form less gibbous, 
•lames Hall has figured it in the Paleontology of the Exploration of the valley of the Great Salt Lake of Utah-, 
by Capt. Stansbury; p. 412; pi. Ill, fig. 6, under the false name of Orthis umbracuhtm. Stansbury found 
it on the banks of the Missouri river above Fort Leavenworth, Kansas. It resembles also the Prod, he- 
misphericus var. minor Keyserling , plate 5, fig. 2 b {See: Reise in das Petsohora Land, im Jahre 1843; 
S' Petersburg, 1846.), which was found in the Mountain Limestone of Podtscher on the Petschora river. 
Locality. — It is found in a siliceous limestone at the western fqot of Delaware Mount on the 
bank of an affluent of the Topofki creek, Texas. This fossil is very common but never well 
preserved, being always a little flattened, and the shell is so thin that it is easily broken or de- 
stroyed. In company with the Productus Delawarii a true urthis is found, but I found none suffi- 
ciently well preserved to be described. 
Explanation of figure. — Plate V , fig. 3. Front view. 
PRODUCTUS CORA d’Orb. 
Plate VI, fig. 4, 4 a. 
Description. — Shell elongated, very gibbous, hinge line very short; etc. (See for the full description; Mono- 
graphic du genre Productus, by L. de Koninck, p. 50; pi. 4 and 5; Liege, 1847. I refer to the same Monograph, 
for the descriptions of all the other Productus.) 
This species as well as all the other Carboniferous Brachiopodae described in this Chapter were submitted to 
de Koninck himself, and also to de Verneuil. and I have followed their determinations. 
Locality. — This fossil abounds in the Carboniferous limestone of the Rocky mountains ; I found 
several dozen specimens in the course of four or five hours exploration , at Tigeras canon of San 
Antonio, at Pecos village, and lastly at the summit of the Sierra de Sandia, at 12,000 feet above 
the sea-level. 
Explanation of figures. — Plate VI, fig. 4. Front view of specimen showing tubercles on the surface. 
» VI, fig. 4 a. Dorsal valve, flattened by vertical pressure. 
The two specimens figured come from Pecos village. 
PRODUCTUS CORA var. MOGOYONl. 
Plate VI , fig. 5. 
Description. — I collected five or six specimens of a Productus , so nearly resembling the P. Cora that 1 do not 
venture to call it a new species, but regard it as a variety, under the name of P. Cora var. Mogoyoni. It differs 
from the P. Cora in the length of the hinge line, which is longer than the transversal axe of the shell, while in the 
P. Cora the hinge line is always shorter. 
Locality. — 1 found this variety of the P, Cora in the Sierra de Mogoyon or Sierra Blanca , near 
the extinct volcano of San Francisco, at camp N° 96, Cedar creek; see: Map A® 2; Reconnais- 
