122 GEOLOGY. 
Propuctus Ivss!, (n. sp.) 
Plate II, figs. 1-8. 
Shell large, transverse; width } greater than extreme length, strongly revolute; beaks pro- 
jecting beyond the cardinal border. Ventral valve: sinus strongly marked, extending from 
near the beak to the anterior border; ears broadly expanded, lateral angles acute; visceral 
region somewhat reticulated and tuberculated; anterior surface striated; striz coarse, nearly 
uniform, and crowned with tubercles; ears covered with rows of tubular spines radiating in 
different directions, of which those on the cardinal border exceed two inches in length. Dorsal 
valve: strongly concave; surface thickly set with spines scarcely exhibiting a determinate 
arrangement. Interior: cardinal tooth ob-conical, narrow, trifid; from it a distinct but slightly 
elevated median ridge extends to the centre of the dorsal valve; hepatic impressions somewhat 
elongated; impressions of the adductor muscles semicircular, with nearly uniform outline; inte- 
rior of ventral valve marked with a strong ridge corresponding with the external sinus, of 
which the surface is striated; muscular impressions quadrate, deep. 
In its general form, and in the magnitude of its spines, this shell resembles P. horridus, but 
in that species the mesial sinus is more profound, the surface much smoother, the tubular 
spines of the wings much less numerous. In the striation and reticulation of the ventral valve 
it approaches P. semireticulatus, but the striz are much coarser, and the tubercles more distinct 
and numerous. There is no species with which I am familiar for which it is liable to be mis- 
en. 
Locality and formation.—Middle Carboniferous limestone, banks of the Colorado, near mouth 
of Diamond river. 
I have dedicated this fine species to Lieut. J. C. Ives, U. 8. T. E., the commander of the 
Colorado exploring party, as a slight acknowledgment of thé unremitting kindness and consid- 
eration received by the members of the scientific corps at his hands. 
PRODUCTUS OCCIDENTALIS, (Nn. sp.) 
Plate I, figs. 9 and 10. 
Shell small or medium size, transverse, strongly revolute, antero-posterior diameter about 
3 the length of the cardinal border. Ventral valve: mesial sinus distinct on anterior surface, 
scarcely reaching the beak; visceral disk somewhat flattened, covered with distinct and rather 
strong tubercles, which toward the anterior border coalesce, to form continuous costa; coste 
18-20; in the sinus 5 or 6 finer than the others; those bordering the sinus remarkably strong, 
broad, and prominent, increasing in width toward the anterior border. The coste of the sides 
of the valve converging toward the beak unite with those of the sinus on the borders of the 
visceral disk, while the most prominent ones bordering the sinus on either side become earlier 
obsolete in the angle formed by the coste of the sinus and those of the sides of the valve; 
‘giving to the shell a peculiar appearance, perceptible at a glance. The wings are broad and 
inflated, with waved edges; the angles slightly rounded; they are separated from the umbo of 
the valve by a distinct sinus. The coste of the anterior surface are tuberculated and bear 
scattered spines. 
_ This shell is nearly related to P. costatus; more resembling the specimens figured by 
_ Sowerby, (Min. Conch. t. 560) than the American variety given by De Konninck, (Monographie 
4. VIII, figs. 3a, 3b, 3c,) but the cost~ bordering the mesial sinus in our shell, so much stronger 
and more prominent than the others, and crowded out by the approach of the lateral and 
central costw, give it a character distinguishing it from that and other species. 
Locality and formation.—The cherty limestone, near the top of the Carboniferous series, 
AS. 13,) banks of Cascade river, near junction of Great and Little Colorados. 
