i 9 i6.] 



Fauna of the Chilka Lake : Terrestrial Isopoda. 



469 



forwards ; its free margin is regularly rounded and fringed in the usual way with short, 

 furry setae, mainly directed towards the median line. 



The left mandible (fig. 6, p. 464) is large and strong, with a powerfully developed 

 molar tubercle ; the cutting-edge is coloured dark brown or almost black and consists 

 of about 3 or 4 stout teeth; the secondary cutting- edge in the left mandible shows a 

 structure similar to that of the outer cutting-edge and consists of 4 stout teeth- 

 Between this and the molar tubercle lies the spine-row of about 15 plumose setae, 

 those nearer the molar tubercle becoming progressively longer than the others ; the 

 molar tubercle which projects inwards somewhat obliquely from the body of the man- 

 dible is very broad and is thickly covered at its distal end with fine, short setae. 



The right mandible (fig. 5, p. 464) is similar to the left, except that the inner cutting- 

 edge is quite different in appearance from the outer cutting-edge, being much more 



Ligia exotica, Roux. 

 Fig. 15. — First pleopod of male with male appendage, seen from the posterior side. 

 Fig. 16. — Second pleopod of male, seen from the anterior side. 



delicate in structure and not coloured brown, and consisting of about 8 or 9 small and 

 very acute teeth. 



The lower lip (fig. 4, p. 463) shows the usual right and left lobes ; they are irregu- 

 larly rounded and thickly fringed with simple setae which also extend along the outer 

 margin. On the posterior side there is a narrow median lobe projecting at right 

 angles to the rest of the lip and in the natural position of the mouth-parts lying be- 

 tween the maxillae. 



The. first maxilla (fig. 7, p. 465) consists of the usual two lobes, the outer one being 

 narrow oblong, about five times as long as broad; its outer margin is slightly convex 

 and bears a fringe of fine setae throughout its whole length ; the extremity is tipped 

 with about 10 long spines, the outer ones being larger and darker than the inner, 

 some of them being dark brown or almost black ; the inner ones are finely serrate 

 along the inner margin. In addition to these spines, there is a long, delicate, 

 plumose seta, longer than any of the spines. The inner lobe is delicate and mem- 

 branous, and on its outer margin it is produced into a thin flange, the more distal por- 

 tions of which bear a thick fringe of setae ; on the inner distal margin it bears three 



