AMPHIPOPA. 257 



Mandibles much hollowed below with a roughened portion, which probably 

 represents the molar tubercle and spine row, in the concave part near the cutting 

 edge ; this is double in one mandible (in which the spine row also is more conspicuous), 

 is expanded, and has 9 strong teeth (fig. 16. m.). 



The palp is as long as the mandible, slender and tapering from the base to a point 

 with a single seta, the joints subequal, the 2nd rather the longest. 



First maxillae : palp 2-jointed, the 2nd the longer ; the outer plate is rather wide 

 and crowned with simple spine-teeth ; inner plate small, quadrate, with rounded 

 corners and a few fine setules on the top (fig. 16. mx. 1 ). 



Second maxillae normal. 



Maxillipeds : inner plate hardly reaching beyond the base of the 1st joint of the 

 palp, with 2 spine teeth a little below the upper margin; outer plate reaching half- 

 way up the 1st joint, with a strong in-curved spine at the outer angle. First and 3rd 

 ioints of the palp subequal and longer than the 2nd ; dactylus rather long and 

 slender (fig. 16. mxp.). 



First gnathopods : 1st joint about as long as the 4th and 5th ; 2nd produced behind 

 in a setose spur about half as long as the hind margin of the 3rd ; the 3rd longer than 

 the 2nd, produced at both angles ; wrist with the hinder part produced in a pointed 

 spur to the end of the hand as in Leucotlwii, with a few stiff setfe on the inner margin. 

 Hand oblong, with the palm at right angles to the hind margin, the angle rounded ; 

 hind margin finely serrate on the distal half, with an intra-marginal row of equidistant 

 spinules ; dactylus rather longer than the palm (fig. 16. gn. 1 ). 



Second gnathopods less powerful than the 1st ; the 1st joint rather longer than the 

 hand with a carina on the distal half of the front margin ; wrist rather less than half 

 as long as the hand, the hind margin prolonged in a setose spur along the hand for 

 about one-third of its hind margin, and ending in a cluster of long spines ; front 

 margin of the hand straight, hind margin evenly curved, without a definite palm, the 

 edge very minutely pectinate and with an intra-marginal row of spinules. Dactylus 

 curved and slender, not reaching the end of the carpal spur, finely pectinate on the 

 inner margin of the proximal half (fig. 16. gn. 2 ). 



First and 2nd peraaopods : side-plates rounded below and obtusely angulated above, 

 the 2nd larger than the 1st; limbs slender and naked, except a few spinules on the 

 front margin of the 5th joint ; 1st joint narrow (fig. 16. pp. 1&2 ). 



The remaining perreopods are like the first 2 pairs, but the side-plates are small 

 and much wider than deep, those of the last pair produced behind to an acute angle. 



First uropods : peduncle nearly twice as long as the smooth, styliform, equal rami. 



Second uropods : peduncle longer than the rami, which are rather unequal, minutely 

 pectinate, and spinulose on the inner margins. 



Third uropods : peduncle shorter than the inner and about as long as the outer 

 ramus; rami styliform, the margins minutely pectinate. 



The 1st uropods extend beyond the 2nd, and these beyond the 3rd. 



2 L 



