| OCR Text |
Show 7 2 DR. H. j . HANSEN ON CRUSTACEANS [Jan. 20, Pacific. S. atlanticus H. Milne-Edw., S. eclwardsii Kr., S. vigilax Stimps., H. J. H., S. tenuiremis Kr., H. J. H., and S. corniculum Kr., H. J. H., have been proved to be distributed through the tropical and subtropical parts of the Oceans almost around the globe, viz., from lat. 23° N., lat. 32° N., or even lat. 42° N. in the Atlantic, throughout the Indian Ocean to Australia, New Hebrides, and " South Pacific." III. Luminous Organs in Sergestes challengeri, n. sp. (Plate X II .) The luminous organs briefly mentioned above are generally easy to discover ; each resembles a very convex, vitreous, faintly yellowish lens, which is circular and sharply defined. They differ much in size, some of them being very small and many proportionately large. It may be advisable, first, to give a conspectus of the organs observed on the single and unfortunately very mutilated specimen, next to add some remarks on their distribution, then to describe their structure, finally to compare them with luminous organs in other Crustacea. Conspectus of the Organs observed. Organs. On each side of the scutum a row with four organs. 8 On the clypeus one organ .......................................... 1 On the lower side of the head one unpaired organ and one near the lateral margin......................... 3 On the lower surface of the thorax and on its infero-lateral margins ....................................................... 26 On the lower side of the third joint of the antenn. ped. one organ ....................................................... 2 On the lower side of each squama four organs....... 8 On the mandible and its palpus two organs ............ 4 On the first maxilliped two organs............................. 4 On the second maxilliped five organs......................... 10 On the first trunk-leg three organs ......................... 6 On the lower surface and on the lateral wall of the first abdominal segment ...................................... 6 Do., do. of the second abdominal segment................ 6 Do., do. of the third abdominal segment ................ 4 Do., do. of the fourth abdominal segment................ 3 On the lateral wall of the fifth abdominal segment. 2 A long the median line of the sixth abdominal segment. 6 On the outer side of the basal joint of each of the pleopods one organ ............................................... 10 On the peduncle and on the inner branch of each uropod two organs ............................................... 4 On the lower side of the outer branch of each uropod two organs................................................................. 4 Total number of organs ... 117 |
