WHITE.) . CRETACEOUS FOSSILS. 19 
ing an oblique, backward-descending curve, ranges nearly vertically. 
Again, the most prominent part of its posterior basal margin is very 
narrowly rounded, instead of forming a regular curve. Its umbonal 
ridges are likewise more prominent, more arched, and extend down to 
the narrowly-rounded posterior-basal extremity. The lobe-like projec- 
tion of the upper part of its anterior margin, under the beaks and in 
front of the umbonal ridge, also differs in being proportionally much 
smaller than in Dr. Reemer’s species, in which it forms about one-third 
of the entire valve, aS seen in side view, while in our shell it scarcely 
forms more than one-sixth. Of course the specimens are more or less 
variable in these characters, but the two forms can always be readily 
distinguished when good examples can be had for comparison. 
‘¢ In its more arcuate form our shell agrees more nearly with Jfodiola 
ornata Gabb, from the Cretaceous rocks of California; but that shell 
differs very markedly in having its beaks decidedly less nearly terminal, 
and a more decided and much more prominent lobe in front of them. 
Another important difference is to be observed in the radiating strie, 
which on the anterior side of our shell are very minute and closely 
crowded, while on that part of Mr. Gabb’s species they are as large and 
distant from each other as on any other part of the valves. 
“If Scopoli’s name, Volsella, should be adopted for this genus, as there 
are some reasons for believing may be the case, this change would re- 
quire the name of this species to be written Volsella multilinigera. 
“ Locality and position.—Cretaceous sandstones near Coalville, Utah.” 
Genus BARBATIA Gray. 
BARBATIA BARBULATA (sp. NOV.). 
Plate 11, fig. 5 a. 
Shell small, longitudinally oblong or subrhomboidal, a little more than 
twice as long as high; cardinal and basal margins nearly parallel, the 
former straight and the latter nearly so; anterior side short, rounded 
up obliquely from the base, and meeting the cardinal margin at an obtuse 
or bluntly rounded angle; posterior side, long; posterior margin, trun- 
cate obliquely downward and backward from the cardinal margin to the 
base, which it meets at a blunted angle, or it is there abruptly rounded ; 
beaks distinct, but somewhat depressed and incurved, placed about one- 
fifth the length of the shell from the front; cardinal area narrow, but it 
is not well shown in our examples. Surface showing fine crowded, raised, 
rounded, radiating striz, which are crossed by fine lines of growth and 
also by numerous sharply raised concentric lines, some of which are more 
conspicuous than the radiating lines. 
Length, about 25 millimeters; height, about 114 millimeters. 
Only two or three imperfect examples of this species have been dis- 
covered, but in its shape and surface markings it presents such differ- 
ences from any known form as to warrant the foregoing description under 
a@ new specific name. 
Position and locality. Cretaceous strata, apparently of the age of the 
Fox Hills Group, at Cimarron, New Mexico, where it was found by Prof. 
St. John, associated with Crassctella cimarronensis White, and other 
forms, some of which were described and figured in Contributions to 
Invertebrate Paleontology No. 1, and published in the Annual Report of 
this Survey for 1877. 
