128 GENERAL ZOOLOGY 



maxillipeds help to hold the food in place at the mouth ; the 

 maxillse also assist in this, and probably, with the upper 

 and lower lip and the wall of the mouth-cavity, are the seat 

 of the sense of taste. The second pair of maxilla} also act 

 as "gill-bailers " (Fig. 68, V, 3-4 ; Fig. 69, 1), which, by their 

 motion, help to maintain a current of water in the gill-chamber 

 (Fig. 69, 5), thus providing oxygen for respiration. In the 

 maxillipeds a basal stem, with two branches arising from it, 

 can be easily distinguished. The separation between head 

 and thorax is understood to come between the second maxillae 

 and the first maxillipeds, thus making five pairs of append- 

 ages in the head-region. 



After the maxillipeds the next thoracic appendages are the 

 large claws, or chelipeds (Fig. 67, 11), composed of seven seg- 

 ments, of which the last two from the body, or distal two, 

 are adjusted to form a nipper, with which the animal captures 

 and holds even rapidly swimming fishes. The remaining 

 thoracic appendages are the four pairs of walking-legs (Fig. 67, 

 12 ; Fig. 68, XI, XII), also composed of seven segments, the first 

 two pairs with nippers at their ends, and the last two pairs 

 without nippers. The three pairs of maxillipeds, the one pair 

 of chelipeds, and the four pairs of walking-legs constitute the 

 eight pairs of appendages of the thorax. 



The Abdomen. There are six pairs of appendages on the 

 abdomen. The first abdominal appendages of the female are^ 

 small, single, and thread-like ; in the male (Fig. 67, 13), they 

 are long and rigid, differing considerably from all the others 

 except the second pair (Fig. 67, 14). The second abdominal 

 appendage in the female is like the third. ' The third, fourth, 

 and fifth pairs, called swimmerets (Fig. 67, 15), are alike in 

 both sexes. The pair of appendages of the sixth somite 

 (Fig. 67, 16) are made up of broad flat branches jointed to 

 a short thick stem, and form, with the last somite, called 

 the telson '(which is without appendages), a strong tail-fin. 



