110 
THIRTEENTH REPORT. 
posterior margins of the last four segments of the first gnathopods of 
both sexes; they are also found on the same places on the second gnatho- 
pods of the female, but appear only on the posterior margins of the fourth 
and sixth segments of the second gnathopods of the male. About 200 
specimens were collected in Lake Catemaco on July 27. They were found 
in large numbers on the stones near shore. 
\ 
DECOPODA. 
7. Cambarus pilosimanus Ortmann. — An adult female (41707) of this 
species was taken from a drainage ditch leading into La Laja creek at 
Cuatotolapam on July 18. Its measurements are as follows: length of 
carapace, 37 ; tip of rostrum to cervical groove, 24 ; width of carapace, 
17 ; height of carapace, 15.6. 
Three young female crayfishes (48708, 41710), about 22 mm. in length, 
collected on the shore of Lake Catemaco, July 27, appear to belong to 
this species. 
8. Cambarus riitkvcni, new species.— -Only two specimens were col- 
lected, a male (41705) and a female (41704). Both were taken as they 
walked along the bank of a ditch in a guarda raya at Cuatotolapam, 
July 25. The female was carrying young that had completed their second 
moult; the male is first form. The characteristics of these two specimens 
are as follows: 
Male: Rostrum subplane, margins elevated, convergent, slightly con- 
vex ; acumen short, hairy below along lateral margins. Postorbital 
ridges slightly converging anteriorly, swollen at posterior end. Carapace 
compressed, plane above, granulated on sides, thickly punctuate above, 
almost smooth behind rostrum; cervical groove sinuate; no lateral spines; 
branchiostegal spine very small, blunt; areola almost obliterated in its 
middle third; posterior triangular space not clearly defined. Abdomen 
narrow, about as long as carapace; basal segment of telson with three 
spines on each side. Epistoma with anterior part triangular, rounded 
at tip. Antennal scale broadest toward the distal end; flagellum reach- 
ing to fourth abdominal segment. First pereiopods elongated, hand 
elongated, somewhat compressed, margins subparallel; surface thickly 
granulate, granules distinct everywhere but more prominent toward 
inner margin; fingers almost as long as palm, both with a smooth ridge 
down the middle of each side, bearing a few tufts of bristles at tip, both 
denticulate on inner margin, the fixed finger with a larger tooth near base. 
Carpopodite with a very shallow sulcus on upper side; granulated every- 
where; granules larger on inner side. Meropodite granulated above and 
below; smooth on inner and outer surfaces; granules on lower surface 
arranged in two rows. Ischiopodite of third pair of legs with a slender 
pointed hook. First pleopods (Fig. 3 A. B) rather short, straight; 
anterior margin with a shoulder near tips; outer and inner parts in close 
apposition to their tips; tip on inner part straight; tip of outer part 
stouter, blunt, bearing a horny spine near tip, flattened on inner face 
with hairs pinnatelv arranged on each side. Length, 58.5 mm.; length 
of carapace, 30; tip of rostrum to cervical groove, 10; breadth of carapace, 
14.6; height of carapace, 14. 
