112 MESSRS. NOEMAN AND STEERING ON THE 



guathopods clearly defined, and the ocular processes in the form of minute 

 isosceles triangles, projecting at the sides of the head between the upper and lower 

 antennte. 



The first of the six following perseon-segments is much the shortest, and subcarinate 

 anteriorly on the ventral surface ; the rest are subequal. 



The pleon has the first five segments subequal, and all of them shorter than the first 

 free perteon-segment ; the last (sixth) segment is longer than two of its predecessors, 

 contracted behind the place of insertion of the uropods, and ending with two slight 

 emarginations, separated from each other by a minute central apex. 



The upper antennae (XXIII. i. aa) lie close together, and. seen from above, com- 

 pletely conceal the lower, which are both shorter and more slender. The upper consists 

 of seven articulations, ihe basal stout and long and slightly bulbous at its origin, the 

 second rather more than one third the length of the first, tlie third still shorter and 

 much thinner, and the first of the flagellum is longer than the three terminal joints 

 combined. The lower antennae are slightly longer than tlie first joint of the 

 upper, and consist of nine articulations, all very slender except the short basal one ; the 

 third is the shortest of those belonging to the peduncle. 



The first gnathopods (XXIII. i. gu^) have the first joint massive, and having the appear- 

 ance, when viewed from below, of the human forearm near the elbow when folded so as 

 to make the muscles stand well out ; the next joint is indistinctly articulated, small, and 

 concealed in some positions of the limb ; tlie third is also small, scarcely visible except 

 on the inner side of the limb ; the wrist is large and subovate ; the liand is also large 

 and strong, with a powerful finger curving over the indented margin of the large thumb, 

 and the horn-coloured nails of the finger and thumb overlap ; the margin of the elon- 

 gate thumb for some distance from the base is minutely beaded, the remainder of the 

 thumb-edge slopes down to the upturned nail in hve irregular blunt teeth, while two or 

 three hairs spring from the side of the thumb ; the inner margin of the finger is a little 

 wavy where it passes over the beaded portion of the thumb-margin. 



The six following pairs of wallving-legs are all slight in structure, the coxal portion 

 and ischium exceedingly small, the basos the longest portion of the limb, the wrist 

 elegantly set with divergent rows of spines. The first three are differentiated from the 

 last three, not merely by the usual tendency to point backwards, while the others tend 

 to point forwards, but by remarkable microscopic differences of the hands and fingers. 

 In the first three (i. gri:) the hand has a small straight dagger-like spine for its finger, 

 ending in a more or less curved, very slender nail, and is almost hidden in a crowd of 

 other spines, some almost as long as, and some shorter than, the finger, but all more or 

 less finely serrated ; the shortest of these spines is liooked at the end, and while smooth 

 on one margin, has on the other six very pronounced teeth at right angles to its length ; 

 adjoining this is another and longer spine, conspicuously serrated on both edges ; in the 

 rest of the spines and in the finger itself the serration is of extreme tenuity. In the 



