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Show 306 MR. E. J. MIERS ON THE PEN.EID^E. [Mar. 5, in the British-Museum collection do not enable me to adopt this course, as many species are not as yet represented in it, I have, in the synopsis of the species given below, and until a more complete revision of the genus shall have become possible, included the species in Peneeus. Synoptic Table of the Species of Penaeus. The object of the following analytical Table is to indicate the principal external characters by which the species of Peneeus may be distinguished. There are certain species which have not been described with sufficient detail to allow of their incorporation in the list; these are either previously referred to, or are mentioned by Milne- Edwards in the ' Histoire Naturelle des Crustaces.' The species of which there are no specimens in the British-Museum collection, and which are therefore unknown to me, are distinguished by an asterisk. I. Antennules with both flagella extremely short. Two deep longitudinal sulci extending along the whole length of the cephalothorax, adjacent to the rostrum and the median carina, which is itself deeply sulcate. (A supraorbital spine present.) First and second pairs of legs bispinose, third pair unispinose at base. Seventh postabdominal segment with lateral marginal spines. 1. P. caramote, Risso. European. First pair of legs bispinose, second pair unispinose, third pair unarmed at base. Terminal segment without lateral marginal spines. 2. P. brasiliensis, Latr. Atlantic region. First and second pair of legs unispinose, third pair unarmed at base. Terminal segment with lateral marginal spines. 3. P. canaliculatus, Oliv. Indo-Pacific region. II. Antennules longer. No lateral sulci on the cephalothorax, bordering the rostrum and median carina. (Supra-orbital spine usually absent.) A. Bostrum much longer than the eyes, reaching nearly to, or beyond, the end of the antennal scale. a. Carapace with a ridge extending backward from the origin of the rostrum to, or nearly to, the posterior margin of the cephalothorax. § The carina between the base of rostrum and posterior margin sulcate, and reaching to the posterior margin. First pair of legs bispinoie, second pair unispinose, third pair unarmed at 7-8 base. Rostrum ---dentate, third to sixth postabdominal segments keeled. O 4. P. semisulcatus, D e Haan. Japan, Indo-Pacific region. First and second pairs of legs unispinose, third pair unarmed at base. Rostrum -^--dentate, curved upward toward the apex; third to sixth postabdominal segments keeled. 5. P. hardwickii, Miers. Indian Seas. 9 Rostrum -jr-dentate, slightly ascending toward the apex. All the postabdominal segments keeled. *6. P. sculptilis, Heller. Java. |
