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



I have examined the oral appendages on the left side and find that the variation 

 from those of the preceding species is but small ; the mandibles are of the same form, 

 with the same kind of synaphipod, while the anterior lip or cheiloglossa fills up the 

 concave hollow within their blades. 



The first pair of siagnopoda differs in having the inner branch a little more slender 

 than the outer. 



The second pair has the margin of the mastigobranchia more densely fringed with hair. 



The third pair is less constricted towards the apex, and the chamber or pocket is 

 less defined, the movable valve is ovate, and the hairs on the inner margin are more 

 numerous. 



The gnathopoda are alike, except that in the second pair the dactylos terminates in a 

 sharper extremity. 



The first pair of pereiopoda is long, narrow, and not unlike that of the preceding- 

 species, excepting some small points of armature. There are two small but conspicuous 

 teeth on the outer margin of the meros, and one on the external distal angle ; the carpos 

 is unarmed excepting a small tooth on the outer distal angle, and the propodos is smooth 

 and free from armature. 



The second, third, and following pairs of pereiopoda do. not differ in any marked feature 

 from those of the preceding species, excepting that the dactylos of the last pair is shorter 

 and fringed with hairs. There is no striking difference in the appendages of the pleon 

 from those of Polycheles baccate 



Observations. — The specimen from which this description was taken was the only 

 one found at Station 218. The only other Crustacean of- this group associated with it 

 was one that I have named Pentacheles obscura, from the uncertainty I feel as to its true 

 character ; it may be a degraded representative of the female of the above. But at 

 Station 170, near the Island of Kermadec, there was taken an imperfect specimen of 

 what I consider may be the female of Polycheles helleri, and the cephalon of which is 

 figured in PI. XV. fig. 1. It corresponds in general character with the male, the 

 ornamentation being slightly different and more distinct. The dorsal surface of the 

 carapace is covered with more defined granular points, from each of which a minute hair 

 springs. The arrangement of small teeth on the median dorsal line is similar in both. 

 There are two small teeth just within the anterior margin at the interior angle of the 

 orbit. The serratures on the lateral margins correspond, but are more pronounced, and are 

 seven in the anterior region, four in the median, and fourteen in the posterior, which 

 gradually lessen in degree and disappear at the posterior margin. The denticulation on 

 the dorsal median ridge of the pleon corresponds with the male specimen, but the increase 

 in size posteriorly is not so conspicuous, and the sixth somite is smooth. 



The tooth on the ophthalmopod is small and there are two teeth (although I have only 

 figured one) near the auditory fissure of the first pair of antennae. 



