PARASITIC COPEPODA. 195 



The first maxillae are straight, small, and weak, and they are fused to the ventral 

 surface of the carapace throughout their entire length, not even the tips being free. 



The second maxillae are also very different from those of T. caudatus. They are 

 two-jointed, the basal joint being fused to the ventral surface of the carapace, and 

 carrying at its centre the rudimentary exopod. This is in the form of a good-sized 

 papilla armed with two setae of about the same length, and less than one-third the 

 length of the endopod. The latter is elongate-triangular, extends for half its length 

 beyond the tip of the mouth-tube, and is bluntly pointed at the end, without any 

 trace of bifurcation. 



The mouth-tube is not as long as in T. caudatus, but is jointed similarly at the 

 centre of the upper lip, with deep lateral incisions. The bony framework shows some 

 similarity to that of both Lepeophtheirus hippoglossi and Caligus rapax. There are 

 in it two sets of rods hinged together at the centre just above the joint (fig. 23). In 

 the basal half the rods are four in number arranged in the form of the letter M. The 

 two outside ones (a) start from just behind the bases of the mandibles and run 

 diagonally forward and inward until they nearly meet at the mid-line. These must 

 be regarded as belonging to the framework of the lower lip, although they are buried 

 in the tissues of the ventral surface of the carapace. From their inner ends two other 

 rods (6) start and run parallel with each other on either side of the mid-line outward 

 nearly to the jointing at the centre of the mouth-tube. These evidently belong to 

 the framework of the upper lip. From the outer ends of the first pair, just behind 

 the bases of the mandibles, a stout rod (c) runs along either side of the under lip, the 

 two curving around and meeting on the mid-line at the tip of the lip. Near the 

 joint in the mouth-tube each of these rods divides and sends a branch rod up to the 

 upper lip, the branch ending in the lateral incision on either side. Articulating with 

 the end of the branch at this incision is a long bone (c/), shaped like the human femur, 

 which sweeps inwards arid forwards until it meets its fellow from the opposite side 

 near the centre of the tip of the upper lip. 



The upper lip is thus jointed near its centre, while the lower lip articulates directly 

 with the ventral surfage of the carapace. As the mouth-tube naturally points 

 backward the upper lip is longer than the lower lip, and this jointing at its centre 

 greatly facilitates the freedom of motion. The mouth-opening is a terminal 

 transverse slit, heavily fringed with hairs. The mandibles are slightly curved 

 towards their tips, where they are toothed on the inner margin. They pass out 

 through the sides of the mouth-tube at the lateral incisions and articulate with the 

 ventral surface of the carapace just in front of the bony framework. 



The first maxillipeds are comparatively large and stout as in T. caudatus, but the 

 basal joint is not as much enlarged, being a trifle smaller than that of the second 

 pair. The two terminal claws are about the same diameter, but the inner one is 

 almost twice the length of the outer. The second niaxillipeds are much reduced 

 in size as compared with those in the Caliginse ; the basal joint is stouter than in 



2 c 2 



