134 GEOLOGICAL SURVEY OF THE TERRITORIES. 
abrupt flexure of those margins to meet those of the other valve. This 
inflection of the posterior lateral margins gives this part of the shell a 
peculiar truncated rectangular appearance, contrasting strongly with 
he very acute angles formed by the connection of the antero-lateralt 
margins of the valves. 
‘“¢ Locality and position.—Hast of Animas River, Colorado, where it 
occurs associated with a small productus of the type of P. subaculeatus. 
According to Dr. Endlich’s sections, as well as from its .affinities, it 
would seem to be’ most probably an Upper Devonian species. Frag- 
ments of it have been brought in from other localities in the Rocky 
Mountains.” 
Genus RETZIA King. 
RETZIA WOOSTERI White, 
Plate 34, figs. 8 a and b. 
Reizia woosteri White, 1879, Bull. U. S. Geol. Sur. Terr., vol. v, p. 215. 
Shell of medium size, moderately gibbous, both valves being nearly 
equally convex; hinge short; ears only Slightly prominent; ventral 
valve having a moderately broad, very Shallow sinus, which is scarcely 
apparent at ‘and near the umbonal region, and produces merely a broad 
sinuosity in the front margin ; longitudinal convexity of the valve regular, 
but greater between the middle and umbo than elsewhere; umbo promin ent 
and somewhat strongly arched. Dorsal valve considerably shorter than 
the ventral, regularly convex, showing only a slight, if any, elevation 
corresponding with the shallow sinus of the ventral valve. Surface 
marked by about twenty-eight simple plications upon each valve, which 
extend from beak to base, being separated by grooves of about equal 
width with the plications. Six or seven of these plications occupy the 
shallow sinus of the ventral valve. They are all of nearly uniform size 
and occupy the whole surface except a small plain space on each side of 
the umbo of the ventral valve, and a still smaller adjacent space on each 
side of the umbo of the dorsal valve. 
Length from ventral umbo to front margin, 20 millimeters; greatest 
width, which is infront of the middle, 18 millimeters; greatest thickness, 
poth valves together, 104 millimeters. 
In general form and character of surface markings this species is re- 
lated to Rk. uta Marcou (= Rk. puncitilifera Shtimard); but, besides being 
a much larger and comparatively less gibbous species, it bears nearly 
or quite double the number of plications upon each valve that is borne 
by A. uta. 
“Associated with it are Spirifer rockymontanus Marcou, Spiriferina oe- 
toplicata Sowerby, Spirigera subtilita Hall, Hemipronites crenistria Phil- 
lips, Axophylium rudis White & St. J ohn, ” and an undetermined small 
Gasteropod. They were all collected by Prof. L. C. Wooster, who, in a 
private communication, says: “They were obtained from some pebbl=: 
in a conglomerate resting upon the eroded face of the granite, 32 miles 
west and 18 miles north of Greeley, Colorado. <A portion of the pebbles 
of this conglomerate was evidently ‘derived from the granite upon which 
it rests.” He found no Carboniferous strata in situ in that region, but 
it is evident that the ‘‘pebbles” which contain the fossils here noticed 
have not been transported to any considerable distance from the ledges 
from which they were derived. The fossils all belong to types which 
are common in the Coal-measure strata, and most of them are well known 
Coal-measure spécies. 
