404 THE VOYAGE OF H.M.S. CHALLENGER. 



furnished at the base with a small lobe that carries a series of membranous cilia, and a 

 small rudimentary second flagellum. 



The second pair of antennae (fig. 2c) is imperfect ; it carries a scaphocerite that reaches 

 nearly to the extremity of the peduncle of the first pair, and is long, narrow, and tapers 

 very gradually to the distal extremity, which is armed laterally at the apex with a 

 sharp tooth, and is fringed on the inner margin with long ciliated hairs. 



The first pair of gnathopoda is short, slender, and feeble ; it is armed on the upper 

 side near the base of the ischium with a small, curved, or hookdike tooth, and furnished 

 at the carpo-propodal articulation with a series of hairs, that, on flexion of the joint, 

 assist in giving a feeble degree of prehensile power. The second pair is very long, 

 being more than two -thirds of the length of the animal. The basal joints are very 

 robust and long, and the terminal two slender, the ultimate being the shorter, and, like 

 the preceding, fringed with hairs. 



The first pair of pereiopoda is small and feeble, the second and third are slender, 

 fringed with hairs, and terminate in small chelae. The fourth is small and feeble, and 

 the fifth rudimentary and inefficient. 



The pleopoda are robust, but not very short, the fifth pair is the shortest, and of the 

 greatest diameter. The sixth pair forms the lateral plates of the rhipidura ; the outer or 

 longer plate reaches but little beyond the extremity of the telson, and is fringed on the 

 outer as well as on the inner side with a series of ciliated hairs, but does not carry a 

 small tooth. 



This species in its general aspect exhibits a close resemblance to Sergestes atlanticus, 

 but may readily be distinguished from it by the absence of the tooth on the outer margin 

 of the external plate of the rhipidura, and by the greater length of the telson. 



The first pair of gnathopoda in Sergestes atlanticus has no armature of any kind, whilst 

 in this species it carries a small tooth near the base on the upper surface, and a brush of 

 prehensile spines at the carpo-propodal articulation. Sergestes atlanticus has been found 

 from Greenland in the north to the Equator. Sergestes edwardsii, besides having been 

 recorded at Greenland by Kroyer, has been found in the North and South Atlantic as 

 well as in the Pacific Oceans. 



Sergestes rinkii, Kroyer (PL LXXIII. fig. 3). 



Sergestes rinkii, Kriiyer, Monograph. Frenistilling af Kraib. Sergestes, pp. 49, G4,Tab. ii. fig. 3, a-g. 



" Eostrum straight and short. 



" Ophthalmopoda very long, reaching to the extremity of the second joint of the first 

 pair of antennae, but not beyond it, clavate, with the ophthalmus ver) T distinct from the 

 pedicle, its width ecpualling the third part of the length of the ophthalmopod. 



" First pair of antennas with the peduncle scarcely shorter than the carapace, exceeding 



