tn the Amphipoda. 375 



Aora and Microdeuteropus will have to be combined * ; and 

 as Aora is the older genus, that name will have to be retained. 

 The specific name typica has priority over all the others, so 

 that the name of our species will be Aora typica. 



I give the synonymy so far as known to me and brief dia- 

 gnoses of the various forms. 



Aora typica. 



. Aora tyjnca, Kroyer, Tidsskr. ser. 2, p. 328, pi. iii. fig. 3 ; Spence Bate, 

 Cat. Brit. Mus. Amphip. p. 161, pi. xxix. fig. 3 ; G. M. Thomson, 

 Ann. & Mag. Nat. Hist. ser. 6, vol. iv. p. 331 ; Trans. New-Zealand 

 Inst. vol. xiii. p. 216. 



Lalaria longitarsis, Nicolet, Gay's Hist, de Chile, iii. pi. ii. fig. 8. 



Microdeuteropus Mortoni, Haswell, Proc. Linn. Soc. N. S. W. vol. v. 

 p. 339, pi. xxii. fig. 2 ; Cat. Australian Crust, p. 264 ; Chilton, Proc. 

 Linn. Soc. N. S. W. vol. ix. p. 1040. 



Microdeuteropus tenuipes, HasweU, I. c. vol. v. p. 339, pi. xxii. fig. 1 ; 

 Chilton, I. c. vol. ix. p. 1040. 



Mio-odeuteropus macidatus, G. M. Thomson, Ann. & Mag. Nat. Hist. 

 ser. 5, vol. iv. p. 331, figs. 5-8; Trans. N.-Z. Inst. vol. xiii. p. 217, 

 figs. 7 A, B, and C ; Chilton, Trans. N.-Z. Inst. vol. xiv. p. 173, 

 fig. 3, a-b. 



Female. Animal smooth, slender. Superior antenna3 con- 

 siderably longer than inferior ; second joint of peduncle long 

 and slender ; third short, and furnished with a 5-6-jointed 

 secondary appendage ; flagellum very slender, many-jointed, 

 sparingly ciliated. Inferior antennse strong, subpediform ; 

 third joint of peduncle short, fourth and fifth very long ; fla- 

 gellum shorter than last joint of peduncle, with stout curved 

 setge in addition to the ordinary slender hairs. Gnathopoda 

 of moderate size, both strongly ciliated ; first pair the largest j 

 propodos about as large as the carpus ; palm very oblique, 

 almost longitudinal, slightly curved, and defined by a strong 

 spine ; dactylos serrated on inner margin ; second pair similar, 

 but with palm transverse or but slightly oblique. Fourth and 

 fifth pairs of pleopoda with stout straight spines ; sixth pair 

 with two or three spines like those of the preceding pairs, and 

 with a few longer and more slender spines or hairs. Telson 

 raised on each side into an upward projection, each having the 

 apex notched and bearing two or three slender spinules. 



Male. Three forms, all differing from the female in the 

 character of the first gnathopod, which in each has the meros 

 produced into a long spine reaching about to the end of the 

 carpus. 



* The necessity for this was indeed recognized by the Rev. T, R. R. 

 Stebbing as far back as 1878. See Ann. & Mag. Nat. Hist. ser. 5, vol. ii. 

 p. 369. 



