GREGARIOUS CRUSTACEA FROM CEYLON. 
7 
are three-jointed, as they are also in T . stanfordi , H. Richardson 
(1901), the genus contains the following species, in all of which 
the joints of the uropods are more than three :—- 
Tanais hirsutus , Beddard, with uropods about 12-jointed, established in 1886. 
Tanais willemoesii, Studer, with uropods 8-jointed, do. 1884. 
Tanais alascensis, H. Richardson, with uropods 7-jointed, do. 1899. 
Tanais novce-zealandice, G. M. Thomson 5-jointed, do. 1880. 
Tanais rohustus , Moore, with uropods 4-jointed, do. 1894. 
Tanais grimaldii, Dollfus, with uropods 4-jointed, do. 1897. 
Tanais chevreuxi, Dollfus, with uropods 4-jointed, do, 1898. 
Tanais testudinicola , Dollfus, with uropods 4-jointed, do. 1898. 
TANAIS PHILETsERlJS, n. sp. 
PI. 2. 
Among numerous examples of Cycithura pusilla there occurred 
a single example of this much smaller species, a female with 
a pair of small ovisacs attached beneath the fifth peraeon segment. 
Its features will be most easily understood by comparison with 
those of the best known Tanais , T. cavolinii , which in general 
character the present species closely resembles, though it is 
considerably shorter and much more slender. 
The cephalic segment is a good deal longer than broad, the 
front rounded, the eye-pieces acute in dorsal view, but in fact 
having rounded margins. The first two pi eon segments have 
the dorsal fringe of plumose setae. The telsonic segment has a 
produced bluntly triangular apex, with a pair of unequal setae on 
each side at the base and an apical pair. 
The two pairs of antennae, the mandibles, and second maxillae 
show no substantial differences from those in the earlier known 
species. The lower lip has the small process at the outer apex 
devoid of setules. The first maxillae have the backward-bent 
“ palp ” ending in only two, not several, setae. The maxillipeds 
in dissection came away in two halves as if not coalesced at the 
base, but as the epipods were lost, the dissection may have been 
a cause of disruption. The subsidiary plate, which reaches to 
the distal end of the ante-penultimate joint, appears to have 
a distal joint, process, or group of setae, set on at right angles 
to its main stem; but as this part in both members was clogged 
with obscuring material, I can only mention the appearance 
and figure it by conjecture. 
The first gnathopods have the hand and finger somewhat more 
robust than in the female of T. cavolinii. It is in the male 
that these limbs are generally distinctive. The slender straight¬ 
fingered second gnathopods agree with those of the species 
just mentioned ; the first and second peraeopods in the hand 
