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



very thin, smooth, turned upwards, and the anterior angle rounded, and fringed with 

 hairs ; the outer anterior angle is armed with a small tooth anterior to the auditory 

 fissure. 



The second pair of antennae has the peduncle quite as long as that of the first, 

 and the scaphocerite is narrow, lanceolate, scarcely reaching to the extremity of the 

 peduncle. 



The several organs of the mouth, so far as they could be observed, appear to 

 have a close resemblance to those of Polycheles helleri ; so also has the gnathopoda. 



The first pair of pereiopoda has the meros smooth to ordinary vision, but a low 

 magnifying power shows several minute points on both the inner and the outer sides. 



The fifth pair of pereiopoda (fig. 2 o, ?) is imperfectly chelate, induced by a short 

 pollex ; the posterior and distal angles of the propodos are produced to half the length 

 of the dactylos ; the dactylos is long, and curved in the same direction as the pollex, 

 its convex or proximal side is smooth, the concave or outer side being hirsute, both 

 forming an imperfect grasping claw. Somewhat similar is the condition of the three 

 posterior pairs ; that is, the dactylos and pollex curve in a direction parallel with 

 each other, and impinge together so that they lie in the same direction instead 

 of opposing each other as finger and thumb. 



The first pair of pleopoda is that of a female, as this specimen undoubtedly 

 is ; and I was much inclined to believe it to be that of Polycheles helleri, but the 

 finding of a specimen, which is evidently the female of Polycheles helleri, off 

 Kermadec Island, has compelled me to hesitate as to the relationship of this specimen. 

 I have, consequently, associated it with those species in which the form of the fifth 

 pair of pereiopoda more nearly resembles this. 



The mastigobranchia attached to the coxa of the second pair of gnathopoda, and 

 the well-developed character of those attached to the pereiopoda, are similar to 

 the same in Pentacheles Isevis. 



Pentacheles Isevis, Spence Bate (PI. XV. fig. 5). 



Pentacheles Ixvis, Sp. B., Ann. and Mag. Nat. Hist., ser. 5, vol. ii. p. 278, 1878. 



Dorsal surface of the carapace long-ovate, free from any armature on the surface 

 except two small teeth equidistant and longitudinally placed on the median line anterior 

 to the cervical fossa. Eostral margin bi-dentate ; inner frontal angle of the orbital 

 notch produced to a strong tooth, serrate on the outer margin. The lateral marginal 

 denticulation is bold anteriorly, gradually decreasing posteriorly. The anterior division 

 is but imperfectly defined from the median, and together they are armed with nine 

 teeth, and the branchial or posterior with fifteen or sixteen. Dorsal median line 

 of the pleon but slightly elevated and imperfectly dentate. The posterior pair of 



