1909. | OF THE THIRD TANGANYIKA EXPEDITION. 61 
Length of adult female 0°86 mm. 
Remarks.—TVhe present form is distinguished from the pre- 
ceding one, to which it bears some resemblance in its external 
appearance, by the comparatively more elongated anterior 
antenne, the quite normal structure of the spines attached to 
the rami of the fourth pair of legs, and finally by the somewhat 
different form and armature of the caudal rami. The distinctly 
ciliated inner edge of these rami is another character by which 
the present species is distinguished, and which has given rise 
to the specific name here proposed. 
Occurrence.—Two female specimens of this form (of which one 
was dissected) were found in a sample from Tanganyika, taken 
28/9/04 at Mbete, south end of the lake. 
32. CYCLOPS OLIGARTHRUS, sp.n. (Plate X XI. figs. 195-202.) 
Specific Characters.— FEMALE. Body (fig. 195) rather strongly 
built and somewhat depressed, with the anterior division ovoid in 
form, frontal part conically produced. Last pedigerous segment 
short but rather broad, and having the lateral parts densely 
clothed with stiff hairs (see fig. 201). Urosome somewhat robust, 
with the genital segment considerably dilated at the base. Caudal 
rami (fig. 202) rather produced, about equalling in length the 
last three segments combined, and slightly diverging; dorsal face 
armed, in front of the very small seta of the outer edge, with an 
obliquely transverse row of very small denticles; all the apical 
setae pronouncedly spiniform and without true cilia, the innermost 
and outermost ones of about equal size; inner mediate seta nearly 
three times as long as the outer, both clothed in their distal part 
with very minute denticles; dorsal seta quite short. Anterior 
antenne (fig. 196) unusually short and compact, scarcely ex- 
ceeding half the length of the cephalic segment, and composed 
of only six articulations densely clothed with coarse sets, some 
of which exhibit a comb-like series of thin spinules on the one 
edge, one of these sets issuing from the end of the first joint 
being particularly strong and extending along the outer part of 
the antenna to its very tip. Posterior antenne (fig. 197) likewise 
unusually short and stout, with the outer two joints imperfectly 
separated and the seta of the basal joint very long. Natatory 
legs (figs. 198-200) resembling in structure those in C. fimbriatus 
Fischer, the middle joint of the inner ramus being very large and 
acutely produced at the outer corner, with the edge in front of 
the latter coarsely spmulose. Last pair of legs (fig. 201) each 
consisting of a single somewhat irregular joint armed with three 
strong spines, the outermost of which is much the largest and 
distinctly denticulate, pointing outwards, so as to project on each 
side of the pertaining segment (see fig. 195). Ovisacs compara- 
tively small, and each containing only a very limited number 
of ova. 
Length of adult female 0°69 mm. 
Remarks.—The nearest ally of this form is unquestionably the 
European species, C. jimbriatus Fischer, with which it agrees in 
