Boone, Crustacea, Cruise of "Alva," 1931 211 



joints and the exopod present. The fifth pair of legs is exceedingly 

 small, rudimentary. 



References: Thysanoessa gregaria, Sars, G. 0., Preliminary 

 Notices on "Challenger," Schizopoda, No. 29 ; Rept. Voy. H. 

 M. S. "Challenger," Zool., vol. XIII, art. Schizopoda, 1885, 

 p. 120, pi. 21, figs. 8-17, pi. 22. 



Genus: STYLOCHEIRON G. 0. Sars 

 Stylicheiron longicome G. 0. Sars 



Plate 61 



Type: Dr. Sars* type was taken by the "Challenger" south 

 of Cape of Good Hope and deposited in the British Museum. He 

 also recorded the occurrence of the species at Messina, in the 

 Mediterranean Sea, in his original description. 



Distribution : In addition to the above cited localities, Dr. 

 Hansen states that this species has been taken in the Atlantic, 

 as far north as south of Iceland, Lat. 63° 08' N., Long. 21° 30' W. 

 He also records it from the Pacific Ocean, from nine "Siboga" sta- 

 tions, between Lat. 4° 27' and Lat. 6° 47.5' S. and Long. 124° 28.2' 

 E. and Long. 129.25° E., in depths ranging from 278 to 1,950 

 meters. 



Material examined : Three specimens, two females and one 

 male, taken in 250 fathoms, off Puerto Cabras, Fuerte Ventura, 

 Canary Islands, Atlantic Ocean, February 18, 1932. Eighteen 

 more specimens from off Nuka Hiva Island, Marquesas Islands, 

 August 10, 1931, depth 150 fathoms. 



Technical description : The adult male measures nine milli- 

 meters long and is very slender; the carapace has the cervical 

 suture very deep ; the precervical portion of the carapace is very 

 little carinate, the rostrum short, acuminate, extending quite to 

 the distal margin of the eyestalk, with the apex a little deflected. 

 The abdomen has the first, second, third, fourth and sixth seg- 

 ments each produced into a small denticle in the median posterior 

 line ; the fifth segment is five-sixths as long as the sixth segment. 

 The epimera are well defined, though not very deep and are evenly 

 rounded. None of the specimens in the "Alva" series has a preanal 

 spine, although adults of both sexes are present. The telson is 

 exceedingly slender, almost twice as long as the sixth segment, 



