1882. | CRUSTACEANS FROM MAURITIUS, 341 
rostral spines shorter, the chelipedes rather slenderer, and the first 
pair of ambulatory legs somewhat less elongated. 
The nearest ally to this species with which I am acquainted is 
Navia (Nawioides) petersii (Podopisa petersii, Hilgendorf, Monatsb. 
Ak. Berlin, p. 785, pl. i. fig. 5, 1878), from Mozambique, which is 
very probably identical with Nawioides hirta, Alph. M.-Edwards 
(Ann. Soc. Entom. France, ser. 4, v. p. 143, pl. iv. fig. 1, 1865), 
from Zanzibar. N. robillardi is at once distinguished by its 
greater size, by having the carapace covered with strong conical spines 
in the place of small irregular tubercles, and by the double hiatus 
in the upper orbital margin. In the last-mentioned character it 
resembles certain species of Pisa (e.g. Pisa (Aretopsis) lanata) ; but 
it is distinguished from that genus by the greater length and slender- 
ness of the chelipedes and first ambulatory legs, by the narrower 
basal antennal joint, and the accessory spines of the rostram ; yet it 
may be regarded as establishing a transition to Pisa. 
In my revision of the Maioidea' I adverted to the insufficiency 
of the characters assigned to Naxioides, A. M.-Edw. (Podopisa, 
Hilgendorf) for distinguishing this genus from Nazia. As the species 
now described has a distinct preocular spine, even this character can 
no longer be cited as peculiar to the last-named genus, 
CALLIANASSA MAURITIANA, Sp, 0. 
Both the specimens sent by M. Robillard are imperfect ; and the 
large chelipede, from which the principal distinctive characters are 
derived, does not appear to belong to either example, but to a 
distinct and larger individual. In the analytical table appended to 
M. A. Milne-Edwards’s monographic revision of the genus Callia- 
nassa*, our new species will be arranged with Callianassa subterranea 
and C. longimana, inasmuch as there exists a small median rostral 
tooth, the terminal segment of the postabdomen and the eyes are 
well developed, and there is a tooth or lobe, which is itself den- 
ticulated, at the proximal end of the inferior margin of the merus 
joint of the larger chelipede, whose penultimate joint or palm about 
equals the wrist in width. It is distinguished from both the above- 
mentioned species, however, by the broad spinulose inferior basal 
lobe of the arm or merus, and by having the distal end of the palm 
between the bases of the fingers deeply excavated as in C. califor- 
niensis and C. uncinata ; the inferior margin of the merus is armed 
with small granulations ; the carpus (in the large chelipede) is some- 
what shorter than the palm, with its upper margin acute; the palm, 
which is not once and a half as long as broad, narrows very 
slightly toward the distal end, its upper margin is rounded, except 
at its proximal end; the lower margin, both of wrist and palm, is 
minutely serrated; the upper or mobile finger is longer than the 
lower, and is sharply uncinated at its distal end, it has a strong 
blunt tooth on its inner margin near the base. I may add that the 
1 Journ. Linn. Soe., Zool. xiv. p. 658 (1879). 
2 Nouvelles Archives du Muséum, vi. p. 101 (1870). 
