CAMBARUS. 35 
12. Cambarus Alleni. 
Plate I. fig. 1, Plate VIII. figs. 2, 2. 
Cambarus Alleni, Faxon, Proc. Amer. Acad. Arts and Sci., XX. 110, 1884. 
Male, form I. — Rostrum broad, triangular, somewhat deflexed, smooth, 
excavated above, margins raised into sharp crests and gradually converging 
to near the tip, where they suddenly come together to form the short, 
sharp acumen; no lateral spines. Post-orbital ridges without spines. Cara- 
pace cylindrical, somewhat compressed laterally, fore border angulated be- 
hind the antennx, punctate above, granulated on the sides. Cervical groove 
deeply sulcated, without lateral spines. Cardiac region more than one third 
as long as the distance from the tip of rostrum to hind border of carapace. 
Areola narrow. Abdomen broad, longer than cephalothorax. Angles of 
pleura rounded. Three or four spines on each side of posterior border 
of basal segment of the telson. Terminal segment of telson shorter than 
basal part, one third broader than long, hind margin concave. Anterior 
process of epistoma subquadrangular. Basal segment of antennules with a 
sharp spme below, near the inner margin, half-way towards the end of the 
segment. Antenne shorter than the body, second and third segments with 
an external sharp tooth. Antennal scale equal to peduncle, slightly sur- 
passing the rostrum, broad, broadest at the middle, rounded at apex, termi- 
nating in a short spine, external margin inflated. Third maxillipeds hairy 
within and below. Chelipeds slender, chela long, subcylindrical, squamoso- 
tuberculate, tubercles ciliate anteriorly, internal border straight, serrate. 
Fingers as long as the hand, with alternate longitudinal ribs and lines of 
ciliate impressed dots. Opposed margins of fingers straight, unidentate. 
Carpus squamoso-tuberculate within, obsoletely so without, with one promi- 
nent spine on inner border. Meros punctate outside, ciliato-tuberculate 
within and on upper margin, which has two ante-apical spmes obliquely 
placed ; two rows of spines beneath. Third and fourth pairs of legs hooked 
on third segments, hooks of fourth pair bituberculate. Fifth pair of legs 
with a flattened laminate tubercle on basal joint. Anterior abdominal appen- 
dages of moderate length, bifid at apex, outer part forming a broad flattened 
plate whose anterior margin is furnished with hairs and one strong seta, the 
‘posterior margin of the plate produced anteriorly into a blunt tooth-like 
process. Inner part bearded within, and produced into a long erect spine, 
which much exceeds in length the outer part of the appendage. 
