REPORT ON THE AMPHIPODA. 891 



fourth pleon-segrncnt has a deep transverse dorsal depression ; the sixth segment runs 

 out into a sharp point on each side of the telson. 



Eyes small, oval, situated near the front of the head almost between the upper and 

 lower antennae. 



Upper Antennas. — First joint much longer and thicker than the second, distally 

 produced into a long acute tooth, and a shorter one minutely and unequally bifid ; the 

 second joint is also distally produced into a bifid tooth of some size on one side and a 

 minute denticle on the other; in the specimen from Station 150 the remainder of the 

 upper antennae was missing ; in a specimen from Kerguelen the third joint was very 

 small, the flagellum longer than the peduncle, of some twenty joints, decreasing in 

 thickness and increasing in length successively downwards (see fig. a.s.). 



Lower Antennae. — First joint forming a small lobe on the lower side, the gland-cone 

 cf the second joint small, the distal margins of both the second and third joints 

 irregularly dentate ; the fourth joint as long as the preceding three united, having 

 distally a produced tooth and a denticle ; the fifth joint narrower and rather shorter 

 than the fourth ; the flagellum longer than the peduncle, consisting of thirty-five joints, 

 of which the first is the longest. 



Upper Lip. — The front plate is wider at the base than at the smooth flattened distal 

 margin, with the sides evenly convex. 



Mandibles long and tongue-like, the cutting edge sloping backwards, so that in the 

 row of seven teeth on the right mandible, three large and four small, the top one is the 

 largest and most prominent ; it has a small tooth on the outer side of it ; on the left 

 mandible the teeth seem to be less numerous and larger ; on the right mandible the 

 secondary plate was obscure ; on the left it was well defined, long, and strap-shaped, lying 

 close to the lower margin of the principal plate, but not reaching its apex, the upper 

 margin convex, the distal part of the lower cut into four teeth ; no spine-row was visible ; 

 the molar tubercle on the left mandible is very small, with a narrow crown minutely 

 denticulate ; on the right mandible no dentate crown could be perceived ; the first joint 

 of the palp is long and distally dilated, with a spine at the inner distal corner, the 

 second joint is longer than the first or third, but is drawn too long in the figures ; it 

 has two spines near the inner apex ; the third joint is a little longer than the first, the 

 outer margin convex, the surface ciliated, the apex and much of the inner margin fringed 

 with spines. In the figures m.m. the new growth of the cutting-plates is seen within 

 the trunk of each mandible, and separate figures more highly magnified are given to 

 show the details of these still-unworn edges. The left mandible is figured on the right, 

 and the right mandible on the left, of the Plate. 



Lower Lip thin in texture, the principal lobes dehiscent, with the inner margins 

 straight or slightly concave, the apex angular ; the inner lobes are doubtfully distinct 

 from the principal ; the mandibular processes are long and divergent. 



