from the Auckland Islands. 37 



Peraeopod 3 almost reaching the end of the fifth joint of 

 per. 4; second joint wide-oval, obscurely serrate and rounded 

 behind. 



Perajopod 4 shorter than 5 which has the second joint 

 angulate and slightly serrate behind, i'ourth and fifth joints 

 not enlarged in male. 



All the limbs are sparsely covered with short spines. 



Telson spoon-shaped, slightly truncate, with spinous 

 margins. 



Length of male 20 mm. ; female 15 mm. 



This species is treated in the ' Tierreich ' as identical with 

 O. serrulata, Dana, which is described as having the perason- 

 segment " encircled by a raised ridge,'' and gnathopod 1 in 

 the female as having the sixth joint ''slightly narrower at 

 apex than base.'' In JSpence Bate's description this limb is 

 said to differ from the male " in being longer and slighter," 

 and his figure agrees with the specimen described in having 

 the sixth joint distinctly wider at the apex; the animal is 

 said to be " very smooth." But for the absence of the 

 expansion of the fourth and fifth joints in perajopod 5 of the 

 male (and it is by no means certain that the specimens 

 examined were sexually adult) this species might well be 

 referred to O. gainmareflus^ Pallas [=0. littorea (Mont.)]. 



Genus Hyale, Kathke. 

 Hyale tri<jonochir^, sp. n. (PI. V. tigs. 5-7.) 



Enderby I., east of Bay. Many males ; four females. 



Perseon-segments subequal ; pleon-segments diminishing 

 in length successively, the third with hind margin rather 

 concave and obscurely crenate, lower margin rather convex, 

 angle subacute. First four side-plates as deep as the 

 segments. Head longer than first segment. Eyes moderate, 

 oblong, widening below. 



Male. — Antenna 1 reaching a little beyond the end of the 

 peduncle of ant. 2, about as long as the head ; flagellum 

 lunger than peduncle, 12-jointed. 



Antenna 2 reaches almost to the third body-segment, third 

 joint the longest ; peduncle and first fifteen joints of flagellum 

 densely setose beneath ; flagellum almost twice as long as 

 the peduncle, 20-jointed. 



Gnathopod 1: side-plate about as wide as long, widening 

 and rounded below. iSecond joint very stout ; wrist more 

 than half as long as the hand and two-thirds of the width of 



* lu allusion to the triangular hand of gnathopod 1 in tlie male. 



