) 
ws 
on 
on 
OF THE COASTS OF SOUTH AMERICA. 
Length 5 lines ; breadth 6 lines. 
Found by Mr. Cuming in considerable numbers with the former. 
MITHRAX PYGMEUS. 
Tab. XI. Fig. 3. 
Mithr. testa depressd, rotundatd, levi ; fronte obtusissimo lato, obsolete bilobato ; pedibus 
anticis corpore duplo feré longioribus ; manibus levibus. 
Hab. ad Panama, Americ Centralis. 
Mus. Soc. Zool., Bell. 
Carapax depressed, broad across the branchial regions, contracted forwards, and ob- 
tuse in front ; the regions rather distinct ; the surface smooth ; the lateral margin with 
a few small teeth or spines. Front very obtuse, obscurely bilobed, laminated. Orbits 
with a minute tooth over the inner canthus, and two externally, much excavated be- 
neath. Eyes large, prominent, globular. 
External antenne with the basilar joint very broad, anteriorly denticulated, the 
moveable portion cylindrical, half as long as the body. External pedipalps with the 
first joint of the inner footstalk nearly quadrate, the second emarginate at the anterior 
and inner angle. 
Abdomen of the male seven-jointed, nearly triangular. 
Anterior feet nearly twice as long as the carapax ; the arm and wrist with a few mi- 
nute tubercles ; the hand robust, smooth ; the moveable finger with a small tubercle 
near the base, the apex excavated and serrated at the margin. The remaining feet 
slender, shorter than the first pair ; having a few tubercles on the first three joints, the 
remainder smooth. 
Colour pale brownish above, reddish beneath ; hands a red brown. 
Length nearly 3 lines, breadth the same. 
Of this little species Mr. Cuming procured two male specimens at Panama, on sand, 
at the depth of ten fathoms. 
The characters offered by this pygmy Crab, are such as to occasion some hesitation 
whether to consider it as a species of Mithraz, or as the type of a new genus. It has 
certainly many important relations to the genus mentioned, and I have preferred placing 
it therein to increasing the number of genera upon what may appear to be too slender 
foundations. The characters in which it differs from the other species, are the smooth- 
ness of the carapax and arms, the slenderness and extraordinary length of the anterior 
feet, the laminated and obtuse form of the rostrum, and the length of the external an- 
tenneé. 
Genus Oruonta. 
Testa laté ovata, rostro parvo, brevi, bifido, haud deflexo, terminata. 
Oculi pedunculo elongato, cylindrico, subcurvo haud crassiores. 
