| OCR Text |
Show 1882.] CRUSTACEANS FROM MAURITIUS, 341 rostral spines shorter, the chelipedes rather slenderer, and the pair of ambulatory legs somewhat less elongated. The nearest ally to this species with which I am acquainted is Naxia (Naxioides) petersii (Podopisa pelersii, Hilgendorf, Monatsb. Ak. Berlin, p. 785, pl. i. fig. 5, 1878), from Mozambique, which is very probably identical with Naxioides hirla, 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 (Arctopsis) 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 rostrum ; yet it may be regarded as establishing a transition to Pisa. In m y 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 Naxia. As the species now described has a distinct prseocular spine, even this character can no longer be cited as peculiar to the last-named genus. CALLIANASSA MAURITIANA, sp. n. 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 Callianassa2, 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 denticulated, 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 somewhat 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^ts proximal end; the lower margin, both of wrist and palm, is minutely serrated ; the upper or mobile finger is longer tban 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. Soc, Zool. xiv. p. 658 (1879). a Nouvelles Archives du Museum, vi. p. 101 (1870). |
