CAMBARUS. 101 
thoracic spine is better developed, the antennx are longer (equal to the 
length of the body), and the tufts of cilia on the inner side of the second 
pair of legs are not developed. The anterior process of the epistoma is not 
notched or truncated. The male appendages and the annulus ventralis are 
as in the typical C. immunis. In the only old specimen (female, 41 inches 
long) the rostrum and epistoma are, unfortunately, mutilated, but the chela 
are broad, as in the typical form, and the second pair of legs show the ciliate 
tufts. I am disposed to consider the variations here as varietal rather than 
specific. The form may be called Cambarus tmmunis, var. spinirostris. 
The only specimens I have seen from the State of New York are a 
pair, so labelled, in the collection of Prof. L. A. Lee. Two specimens in 
the U.S. National Museum, male, form Ii., and female, from Orizaba, Mexico, 
(Prof. Sumichrast,) do not differ to any extent from those inhabiting the 
United States. 
42. Cambarus Mississippiensis. 
Plate ITI. fig. 2, Plate X. figs. 4, 4, 4a, 4a’. 
Canbarus Mississippiensis, Faxon, Proc. Amer. Acad. Arts and Sci., XX. 123, 1884. 
Male, form I.— Rostrum broad, twice as long as broad, subexcavated 
above, smooth, foveolate at base, margins raised, converging anteriorly, sinu- 
ate at apex; acumen short, triangular, acute, no lateral teeth. Post-orbital 
ridges suleate on outer side, with short, blunt anterior spines. Carapace 
densely punctate, sides lightly granulate, front lateral border not angulated. 
Cervical groove sinuate, with small lateral and branchiostegian spies. Areola 
linear anteriorly to the middle, with a small anterior and a larger posterior 
triangular field. Length of areola equal to half the distance from tip of 
rostrum to cervical groove. Abdomen as long as the carapace. Terminal 
segment of the telson shorter than the basal segment, hind border slightly 
concave at the centre ; basal segment bispinose on each side. Anterior angle 
of epistoma notched. Sternum between the legs densely ciliated. Antennal 
scale very broad, apical spine short. Third maxillipeds hairy without and 
beneath. Chele large, punctate, smooth below, margined without; inner 
margin of hand short, furnished with dentiform tubercles irregularly disposed 
in a double series ; a little distance from these is another line of smaller cili- 
ated tubercles on the upper surface of the hand on a line with the middle 
of the base of the movable finger. Fingers long, gaping at base, each with 
