CAMBARUS. 93 
C. ais, and more closely C. Putnam’; but the young of the first may 
be distinguished by the carinated rostrum; of the second, by the longer 
rostral acumen, antennal scale, and anterior spine of post-orbital ridge, by 
the longer hand and internal carpal spine, and by the divergent tips of the 
first pair of abdominal appendages in the male ; of the third, by the longer- 
spined antennal lamina, and the long, deeply cleft abdominal appendages of 
the male. 
In C. obscurus Hag., which I deem a local form of C. propinguus, the ros- 
trum is somewhat broader, not carinate above, and less deeply hollowed out 
than in the typical C. propinquus ; the hand is broader, with a few tubercles 
disposed in a longitudinal row opposite the base of the movable finger; the 
fingers are more widely separated at the base, the epistoma more truncate ; 
the male appendages have a projecting angle or shoulder on the anterior 
margin at the base of the rami, the outer part often grooved longitudinally 
on the outer side. This form has been discovered only at Rochester, N. Y, 
The differences between it and C. propinquus are so slight that I consider it 
only a variety. Some specimens of C. propinquus show a strong tendency to 
develop the projecting shoulder on the front border of the male appendages. 
In the United States National Museum is a small first-form male of a 
Cambarus labelled ‘“ California” (No. 2531), which I cannot distinguish spe- 
cifically from C. obseurus. The areolar part of the back of the carapace is 
a little flatter, and the row of small tubercles on a line with the middle of 
the base of the movable finger is not apparent; but this often happens 
in small specimens of C. obscurus. The locality of this specimen is very 
probably erroneous, as no other specimen of a Cambarus from the west coast 
is known. 
Hagen thinks that C. obsewrus may be the Astacus fossor of Rafinesque. 
Rafinesque’s description is as follows : — 
“ Astacus fossor. Antens length of the body, rostrum short, one-toothed 
on each side, a thorn behind the eyes; three pairs of pinciferous feet, hands 
of the first pair very large, granular, gaping, toothed, with a furrowed and 
bispinous wrist.— Obs. Vulgar name, burrowing lobster, —communicated to 
me by Dr. Samuel L. Mitchill, —native of Virginia, Pennsylvania, and New 
York; size from four to six inches; it burrows in meadows and milldams, 
which it perforates and damages.” 
It is impossible to determine what species is here meant. The descrip- 
tion would suit C. propinquus, a commoner form, as well as C. obseurus. 
