WHITE.] CRETACEOUS FOSSILS. ont. 
ARTICULATA. 
CRUSTACEA. 
Genus PARAMITHRAX Milne-Edwards. 
PARAMITHRAX ? WALKERI Whitfield. 
Plate 16, fig. 1 a; and Plate 17, fig. 1 a. 
Both description and figures of this Brachyuran have been furnished 
by Prof. R. P. Whitfield for this report, for which he is sole authority. 
It is an exceedingly interesting addition to our knowledge of the Creta- 
ceous Crustacea; and especially so because remains of this class are so 
rare in American Cretaceous rocks. 
“This species is represented only by the claw and part of the penul- 
timate joint of the right anterior limb. The specimen is of a short, rather 
compact and robust form, and somewhat triangular in transverse section. 
The length of the hand, from its articulation with the preceding joint to 
the base of the fixed mandible, bears the proportion to the height and 
thickness that seven does to five and four; the latter measurement being 
exclusive of the nodes. The mandibles, both fixed and movable, are 
distinctly round, without any flattening or carination; are gently and 
nearly equally curved throughout their length, and the articulating pro- 
cesses strong and robust. The hand is somewhat flattened on the inside 
and angular on the outer surface; the angulation being rather below 
the middle of the height, giving it the triangular form. The next pre- 
ceding joint is only preserved in part; it is strong, obliquely ovate in 
form, and provided witha large flattened basal projection near the inferior 
articulation. 
‘‘ Surface of the specimen, with the exception of the inner face of the 
mandible, marked by numerous strong spine-like nodes or tubercles, 
which have probably been spines on the surface of the shell (the speci- 
men being ap internal cast). These nodes are arranged in longitudinal 
lines on the outside of the claw, and partly so on the inside; but on the 
latter there is also a line of large nodes extending obliquely downward 
from the upper edge, parallel to the margin of the socket of the mova- 
ble mandible, and at a short distance from it, and continuing upon the 
mandible. The preceding joint is also marked by lines of strong nodes ; 
a double transverse line on the inside parallel to the anterior margin, 
but divided from it by a broad, rounded channel, and a single line of 
stronger nodes on the outside. The flattened area forming the basal 
projection of the joint is also bordered by nodes. 
“The specimen, being an internal cast only, does not furnish the exact 
features of the shell itself, and as there is only a part of the limb known 
it is difficult to determine the generic characters in a satisfactory man- 
ner. There would appear to be but littie reason to doubt, ‘from its 
spiny character and the round claws, its relations to the group com- 
monly called spider-crabs. Still there are some features which seem to 
differ from those of the generality of the species of that group, and it is 
therefore with some hesitation that I have referred it to the family 
Maiade, and still more doubtfully to the genus Paramithrax; but I am 
not able to find any genus of strictly fossil crustaceans to which it 
