| OCR Text |
Show 1882.] CRUSTACEANS FROM MAURITIUS. 541 smaller spines ; the wrist has its upper margin subcarinated, with spine at the distal end, behind which are several granules,- the palm is nearly three times as long as broad, laterally somewhat compressed, with the upper and lower margins subacute-the upper armed with ten small tubercles and with a short spine placed above the base of the dactylus, which is much thickened at base and has its inner margin unarmed ; except for a small tubercle at base, it curves downward nearly at right angles with the base against the small immobile finger, which is armed with two blunt teeth on its inner margin. The ambulatory legs are slender and smooth; the merus joints are armed below with a small distal spine, and are longitudinally canaliculated on their outer surface ; traces of similar canaliculi are seen upon some of the following joints, and particularly of the dactyli, which are hairy. The distal portions of the terminal segment and uropoda are membranaceous and minutely spinulose as in the typical Palinuri, the margins of the indurated parts being denticulated nearly as in P. vulgaris. The ground-colour of the carapace (in the dried example) is red, blotched or variegated with yellow; the postabdominal segments are orange-red, minutely punctulated with yellow ; and the first to fifth segments have a transverse series of large yellowish-white spots bordering their posterior margins and the margins of the lateral lobes and spines ; the flagella of the antennas are alternately banded with yellow and red; the ambulatory legs are orange-yellow, with numerous irregular yellowish-white spots. The length of the body is a little over 6 inches (152 mm.), of the left chelipede about 63 inches (160 mm.), of the first ambulatory legs nearly 4\ inches (108 mm.). The unique example being dried, and the parts not always fully extended, it is difficult to give the exact measurements. A single adult male is in the collection (preserved dry). The Mauritian variety is to be distinguished from the West-Indian type of P. longimanus (if Prof. A. Milne-Edwards's outline drawings may be referred to for these minute details) only by the minute or obsolete second lateral postocular spine, the stouter leg of the first pair with more robust palm and stronger abruptly-curved dactylus, by the much greater development of the spines of the peduncular joints of the antennae, and the existence of a spinule behind the long lateral spines of the second to fifth postabdominal segments-distinctions which, even if they exist, assuredly cannot be regarded as of specific importance. Although P. longimanus differs so markedly from its congeners in the form and great development of the chelipedes, in what are usually regarded as the essential generic characters-i. e. in the distinct rostrum, the narrow antennal segment, approximated bases of the antennae, and short anteunulary flagella-it belongs, as already stated, to the typical Palinuri. The genital apertures are situated upon a slender styliform prolongation of the coxal joints of the fifth ambulatory legs, which is directed inward toward the middle line of the sternum, and bears a small spine near the distal extremity. In P. vulgaris the rounded |
