REPORT ON THE AMPHIPODA. 1353 



Phronima megalodous, n. sp. (PI. CLXIL, A.). 



Seventh segment of the perseon longer than the first of the pleon ; postero-lateral 

 angles of the first three segments of the pleon acute. Branchial vesicles respectively 

 longer and broader than the first joints of the limbs. 



First Gnathopods. — The produced wrist longer than the hand, its distal margin very 

 sinuous, the produced hinder apex not half the length of the hand, its convex inner or 

 front margin very regularly pectinate ; the hand very scabrous. 



TJie First and Second Perseopods with hind margin in the first and second joints only 

 slightly prominent j ust above the apex, not at all produced or acute. 



Third Perseopods. — As usual the first and second joints are thickened and more or 

 less channelled behind and sharp-edged in front, while in the third joint and in the fourth 

 at its upper part the hinder margin is sharp, the front of these joints being broad. The 

 first joint is large, widening considerably as it approaches the distal end, where the hind 

 margin of the outer surface forms an angle but is not produced into a tooth ; the front 

 margin of the second joint forms a tolerably acute apical tooth ; the third joint is rather 

 longer than the second, with a narrow neck, below which the hind margin is very convex, 

 the front straight with rounded apex ; the fourth joint is as long as the first, twice as 

 long as its greatest breadth, the neck narrow, the front margin sinuous, distally forming 

 a considerable tooth which may be reckoned as about a fourth of the total length of the 

 joint ; a deep cavity separates this tooth from one not much smaller occupying the centre 

 of the palm, its front edge smooth, its longer hinder margin being distally divided into 

 five little teeth or crenulate compartments ; beyond this the palm has a rather irregular 

 course, but without teeth, on either side of the base of the following joint ; the finger-like 

 fifth joint is curved, not so long as the fourth joint, but when closed upon it projecting 

 much beyond the front tooth of that joint, having its front or inner margin a little 

 bulging and crenate for a short space where it begins to emerge beyond the tooth ; the 

 finger is as usual minute and strongly bent. On the inner surface of the fourth joint 

 between the bases of the two teeth there is a little rounded process carrying a setule. 



Fourth, Perseopods. — The first joint considerably shorter than in the preceding pair, 

 as long as the three following joints together, with a minutely produced apex of the front 

 margin; second joint of the front margin strongly bent, and excavate below the quasi- 

 apical angle; the third joint longer but much narrower than the second, the upturned angle 

 at the top of the front margin not strongly produced, the distal margin as usual oblique; 

 the fourth joint considerably more than twice as long as the third, and nearly twice as 

 long as the fifth. 



Fifth Perseopods similar to the fourth, but with the first joint much longer, the 

 others shorter, especially the third and fourth ; the fourth joint nearly twice as long as 

 the third, and considerably longer than the fifth. 



(ZOOL. CHALL. EXP. PART LXVIL 1888.) Xxx 170 



