REPORT ON THE AMPHIPODA. 929 



comparison. The likeness between the two species makes it probable that they belong 

 to the same genus ; the distance between the localities at which they were obtained adds 

 a little to the probability that they are in fact specifically distinct. 



Atylopsis dentatus, n. sp. (PI. LXXX.). 



Rostrum small, rounded, lateral lobes of the head not prominent, with sinuous out- 

 line ; last segment of the perseon and first two of the pleon each dorsally produced back- 

 wards in a small tooth ; first three segments of the pleon with the postero-lateral angles 

 also produced in a small tooth, the lower border of the segment having a conspicuous 

 spine ; the integument rather hairy. 



Eyes round, oval, near the front of the head, with slender ocelli. 



Upper Antennae. — First joint shorter than the head, longer than the second joint ; 

 second joint not much longer than thick ; the rest missing. 



Lower Antennae. — First three joints short, gland-cone decurrent ; fourth joint shorter 

 than the first three united ; the rest missing. 



Upper Lip bilobed, very finely ciliated, one lobe more advanced and much broader 

 than the other. 



Mandibles. — Cutting plate divided into seven or eight teeth ; secondary plate of the 

 left mandible divided into five or six teeth, of which the lowest is the longest ; on the 

 right mandible the secondary plate is slighter, distally bifid, with two slender teeth 

 conspicuous, the lower one the longer ; spine-row of six plumosely serrate spines mixed 

 with long cilia ; close to the spine-row is the molar tubercle, the crown of which has 

 several rows of strong denticles and a plumose seta ; set just over the tubercle is the 

 strong palp, the first joint a little dilated distally, the second rather stout, with a few 

 spines near the front margin ; the third joint as long as the second, with nine spines 

 on the upper part of the front margin and the apex, of which the two actually at the 

 apex are the slenderest, the others being broader and conspicuously pectinate on two 

 edges ; near the base, on the surface near the convex hind margin, are two pectinate 

 spines, one much longer than the other, boldly pectinate in its lower part, and finely in 

 the upper. 



Lower Lip. — Principal lobes broad, distally somewhat narrowed and dehiscent, lightly 

 ciliated ; inner lobes short ; mandibular processes short, blunt-ended. 



First Maxillae. — Inner plate small, with two setse on the apex ; outer plate carrying 

 on the truncate distal margin ten spines, the three shortest of which are furcate, the 

 others denticulate ; the second joint of the palp reachiug beyond the outer plate, broadest 

 near the distal margin, which is dentate and has four spine-teeth of different lengths, 

 besides two or three slender submarginal spines. Though only ten spines were seen on 

 the outer plate, it is probable that the normal number is eleven. 



(ZOOL. CHALL, EXP. PART LXVII. 1887.) XxS 117 



