REPORT ON THE AMPHIPODA. 1249 



1876. JEgina, Sais, Prodr. descr. crust, ei pycn., p. 361. 



1> S 77. „ Miers, Ann. and Mag. Nat. Hist., ser. 4, vol. xx. 



1882, „ Mayer, Die Caprelliden, p. 33. 



1882. JZginella, Mayer, Die Caprelliden, p. 36. 



1885. JBginOi Sars, Den norske Nordhavs-Exp., p. 228. 



1887. „ Hansen, Oversigt over de paa Dijmphna-Togtet indsamlede Krebsdyr. 



Since the name JEgina given by Kroyn- was preoccupied, and Mayer has shown that 

 in all probability Boeck's genus JEginella is identical with sEgina, the latter name will 

 take the place of the earlier. For Kroyer's definition, see Note on Kroyer, 1843 (p. 202), 

 and for Boeck's, see Note on Boeck, 1860 (p. 325). The definition will at present stand 

 as follows : — 



Mandibles with a three-jointed palp. 



Lower Antenna? with a two-jointed flagellum. 



First and Second Perasopods wanting, the other limbs of the perseon normal. 



Branchial Vesicles only on the third and fourth segments of the perseon. 



PleOn one-jointed. 



The only distinction drawn by Boeck between JEgina, Kroyer, and his own AZginella 

 was that in the former the first uropods were two-jointed, and in the latter one-jointed. 

 Mayer thinks that this distinction may have been due to an error of observation. In any 

 case it may, I think, be allowed to rank as not more than a specific difference. In the 

 new species here assigned to the genus the uropods were not present. 



JEginella tristanensis, n. sp. (PI. CXLIIL). 



Head with the dorsal margin rounded in front ; behind the middle there rises a 

 little blunt tooth, directed slightly forwards, and having a cilium at its base behind ; 

 the first segment of the perseon is intimately coalesced with the head, its dorsal margin 

 shorter, its ventral longer than the head ; the second segment shorter than the third, 

 dilated in front except at the neck, with a minute tubercle dorsally in front of the centre ; 

 the third segment longer than the fourth ; the fourth than the fifth ; the fifth than the 

 second ; the sixth longer than the seventh, these two together not cpaite so long as the 

 second. Pleon as in Caprellinopsis tristanensis. 



Eyes small, round, with about eighteen ocelli, not all of the same size, nor set very 

 close together. 



Upper Antennae. — First joint nearly as long as the top of the head ; second nearly 

 as long as the first and third together ; third more than half the length of the first, 

 widening distally ; flagellum rather longer than the peduncle, consisting of seven 

 elongate unequal joints, each except the first with a slender apical filament and some 

 cilia, the first joint the longest, longer than the third joint of the peduncle, the second 

 joint the shortest, less than half the length of the first. 



(ZOOL. CHALL. EXP. — PART LXYII. — 1888.) Xxx 157 



