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



Remarks. — The specimen described is a female. The specific name refers to the 

 apical serration of the telson. 



The species has some remarkable resemblances to Amphithopsis longimana, Boeck, 

 from which however it is clearly distinguished by its cleft telson. It is also generically 

 distinguished from Amphithopsis by the spine-teeth on the inner margin of the outer 

 maxilliped plate, but it should be noticed that while Boeck gives to this part in 

 Amphithopsis the generic character spinis tenuibus instructa, he states that the species 

 Amphithopsis longimana has it furnished with teeth, " den ydre Plades hele indre Rand 

 er vaebnet med taetstaaende, men korte Taender." 



Genus Atylopsis, n. gen. 



Upper Lip with the distal margin more or less bilobed. 



Mandibles with strong palp ; the third joint as loug as the second. 



First Maxillae with a few setae on the distal margin of the inner plate. 



Second Maxillse with some plumose setas on the surface of the inner plate. 



Maxillipeds. — Outer plate without teeth on inner margin, not reaching the apex of the 

 palp's second joint ; third joint of palp apically produced over the base of the finger. 



Antennae with short peduncles. 



First and Second Gnathopods similar in shape, the second larger than the first. 



Uropods of the first and second pairs with the outer branch shorter than the inner ; 

 peduncles of the third pair short. 



Telson subequal in length to the peduncles of the third uropods, cleft or emarginate. 



The generic name points to the likeness between this genus and the Atylinae of 

 Boeck, although the upper lip is not apically rounded but incised. 



From Pontogeneia, Boeck, which it closely approaches, it is further separated by 

 having the third joint of the mandibular palp equal in length to the second, instead of 

 much shorter. 



From Pherusa, Leach, and its synonym Amphithopsis, Boeck, another near ally, 

 it is distinguished both by the incised upper lip and by the telson being more or less 

 divided ; Amphithopsis longimana, indeed, has the apex of the telson a little incised, but 

 that species disagrees with the generic definition both in this respect and in having teeth 

 on the outer plate of the maxillipeds. 



Had the type species of Pherusa, Leach, been anywhere described in detail, it might 

 have been advisable to group the species of the present genus provisionally with it, but 

 since the published descriptions of Pherusa fucicola only refer to the external characters, 

 no advantage was to be gained by adopting a name which might afterwards prove more 

 unsuitable than it seems at the moment. Boeck uses the shape of the distal margin of 

 the upper lip as one of the characters by which he distinguishes his subfamilies ; whether 



