12 Bulletin American Museum of Natural History [Vol. LIII 
Stanleyville, April 1915, about 515 (49 ovig. 9). Avakubti, October 
7, 1909, about 200 (7 ovig.). Niangara, November 1909, 11%, 19°. 
Faradje, January 1913, about 141 (19 ovig.). 
Beni lies to the east of the Congo-Nile divide. Lenz’s statement (in 
the tabular summary of the distribution of his material) places his C. ¢. 
var. breviatus 20 kilometers northwest of Beni. An orographical map 
published in 1918 by the Royal Geographical Society of London shows 
that a river lying in that direction might well belong to the Congo 
watershed, although the map accompanying Schubotz’s preliminary 
account of the German Central African Expedition! seems to place these 
specimens within the Nile watershed, an occurrence of, considerable 
interest with respect to the geographical distribution of the Crustacea of 
the Congo region. 
MEASUREMENTS.—Of the largest specimen observed, a female from 
Stanleyville: length of rostrum, of which the extreme tip is missing, 5.5; 
preorbital length of antennular peduncle, 4.25; post-orbital length of 
carapace, 5.5; depth of carapace, 4; length of abdomen about 18; length 
of telson exclusive of terminal spines, 3.5 mm. 
Drscriprion.—A much more variable species than hitherto realized by authors. 
The rostrum varies in length, reaching from about as far as the middle of the last 
segment of the antennular peduncle to, in exceptional cases, twice the length of the 
last segment beyond the end of the antennular peduncle. Most specimens seem to 
have the rostrum a little longer than the antennular peduncle. The rostrum varies 
in both shape and direction; sometimes it is directed a little downwards proximally, 
while distally it is ascendant with a very slightly curved tip; in some specimens the 
upper outline is slightly convex, but in many it is quite straight. The length of the 
free portion of the rostrum, as compared to its depth, varies from about 5 to 8.3 times 
as long as deep, not including the dorsal spines. 
Of the 153 specimens tabulated below the dorsal rostral teeth range from 10 to 
29 in number; of these from 2 to 6 may be on the carapace, though in the specimens 
with 28 teeth but 2, and in one with 29 teeth, but 3 teeth were situated on the cara- 
pace. The more usual number of dorsal rostral teeth lies between 14 and 22, the 
greater number of specimens having 17, 18, or 19 teeth; of these the greater number 
of specimens have 3 teeth on the carapace. Below, the teeth vary from 3 to 17 in 
number; the more usual range, however, being 6 to 12; the greater number of speci- 
mens had 7, 8 or 9. The tooth-free portion of the rostrum varies considerably above 
and below. In any large series about 50 per cent of the specimens will have the 
unarmed distal portion well marked, occupying dorsally in one case more than one- 
third the length of the free portion of the rostrum; in the remaining 50 per cent the 
teeth, above and below, run quite close to the tip, practically eliminating what might 
be called a tooth-free portion. 
11909, Sitzb. Gesell. Naturf. Freunde Berlin, pp. 383-400, 1 map. 
