OCR Text |
Show 548 REV. T. R. R. STEBBING ON CRUSTACEANS [May 22, the penultimate joint is fully two-thirds the length of the antepenultimate. On the other hand, the specimen here identified with macrura has the three terminal joints of its second maxillipeds together longer than the fourth joint, and the antepenultimate thrice as long as the penultimate. But as Sars considers that none of his specimens were full-grown, I abstaiu from regarding the differences mentioned as of specific value. Mr. Vallentin's specimen, of which unfortunately I cannot give the measurements, was certainly longer than the 13 m m . reached by Sars's specimen. Locality. Stanley Harbour, Falkland Islands. ISOPODA. A S E L L O T A. 1882. Asellota, Sars, Christiania Vidensk. Forh. no. 18, p. 58. 1885. Asellota, Sars, D e n Norske Nordhavs-Exp. vol. xiv. pt. 1, p. 118. 1893. Asellota, Stebbing, Hist. Crust., Internat. Sci. Ser. vol. lxxiv. p. 376. 1895. Asellota, Hansen, Isop., Cumac. u. Stomat., Plankton- Exp., p. 4. 1897. Asellota, Sars, Crustacea of Norway, vol. ii. pt. 5, p. 94. Fam. JANIRID.E. 1897. Ianiridce, Sars, Crustacea of Norway, vol. ii. pt. 5, p. 98. The genus Janira, Leach, 1813-1814, established in the Supplement to his article " Crustaceology," was not spelt with an initial iota, but was trisyllabic. Gen. LAIS Bovallius. 1886. Iais, Bovallius, Notes on Fam. Asellidae, pp. 4 & 50, Bihang K. Svenska Vet.-Akad. Handl. vol. xi. no. 15. 1886. Jcera (part), Beddard, ' Challenger' Isopoda, Beports, vol. xvii. p. 19. 1887. Iais (Janthe), Pfeffer, Krebse von Siid-Georgien, p. 18. This genus may be distinguished from its very near neighbour Jcera Leach, by the narrowness of the body, the smallness of the eyes, the triunguiculate fingers on all the limbs of the peraeon, and by the uropods which are not adjacent, not inserted in a notch of the pleon, and in which the peduncle is not longer than the rami. O n the last only of these four characters can much dependence be placed. Sars, indeed, in his definition of Jcera includes the character " dactylar joint 3-unguiculate," but the reckoning of spines which justifies this would allow us to say that the dactylus in Iais was quadriunguiculate. It is, however, a somewhat unsubstantial character. Still more so are those depending on the breadth of the body and the size of the eye. In the mouth-organs |