1909. | OF THE THIRD TANGANYIKA BXPEDITION. oT 
(see fig. 27) wholly coalesced with the preceding one, and having 
the lateral parts quite simple, not expanded laterally, each with a 
very delicate hair-like point on the outer edge (fig. 28). Urosome 
(fig. 27) rather slender and narrow, and perfectly symmetrical ; 
genital segment slightly widening in front and without any 
lateral mucros; the last two segments confluent, and combined 
fully half the length of the genital segment. Caudal rami some- 
what more produced than in the three preceding species; marginal 
sete normal. Anterior antenne slender and elongated, when 
reflexed exceeding the body by the last two joints (see figs, 25 & 
26). Last pair of legs (fig. 29) comparatively large; imner ramus 
scmewhat exceeding half the length of the proximal joint of the 
outer and finely ciliated on the tip; claw of this ramus com- 
paratively short and thick; terminal joint extremely minute, 
nodiform, with the inner apical seta not extended to the tip of 
the claw. Ovisac rather large, broadly rounded in form, and 
containing a greater number of ova than ina ny of the preceding 
species. 
Mate with the antepenultimate joint of right anterior antenna 
(fig. 30) produced at the end to a slender spiniform process 
slightly curved at the tip, and fully as long as the penultimate 
joint. Last pair of legs (fig. 31) with the squamiform expansions 
of 1st basal joint, as in JD. stwhlmanni, simple, not spiniferous 
2nd basal joint of right leg without any projection at the end 
proximal joint of outer ramus terminating outside in an obtuse 
corner; distal jot broadly oval in form and without any scale- 
like projection of the posterior face; lateral spine comparatively 
short and attached much nearer to the end than the base of the 
joint ; apical claw of moderate size and only slightly curved. Left 
leg with the outer ramus pronouncedly spoon-shaped and uni- 
articulate, inner edge evenly curved and minutely spinulose ; 
terminal digit very small and partly concealed, accompanying 
bristle likewise small; anterior face of the ramus provided with a 
small linguiform lamella, finely ciliated at the edge (see fig. 52). 
Length of adult female 1:10 mm. 
Remarks.— this is a rather small species, and is prominently 
distinguished not only from the four preceding species, but also 
from most other known Diaptomi, by the simple, not expanded 
lateral parts of the last segment of metasome in the female; hence 
the specific name here proposed. 
Occurrence.—This form occurred rather abundantly in two of 
the samples from Tanganyika, the one taken 18/11/04 off Kala, 
eastern shore of the lake, the other 1/3/05 off Kaboge, north- 
western shore. It was also found occasionally in some other 
samples, and seems indeed to be one of the most characteristic 
plankton-forms of that lake. 
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DIAPTOMUS CUNNINGTONI, sp.n. (Plate TX. figs. 33-42.) 
Specific Characters.— Fumaue. Body (figs. 33 & 34) compara- 
tively short and stout, with the anterior division somewhat 
