222 DE. C. CHILTON ON THE SUBTERRANEAN 



rows of setoe, each containing four or five, tbe lateral surface of the joint also hearing 

 two or three small tufts of seta?; the fifth joint is as long as the fourth, but rather more 

 slendei", armed with setae in a similar way to the fourth, but with more numerous tufts ; 

 the flagellum shorter than the fifth joint, consisting of five joints, of which the first is 

 the longest ; the articulations between the joints are oblique, and each bears at the 

 extremity a row of four or five small setae, and there is another row of four or five rather 

 longer seta? on the lower margin towards the extremity. 



The tipper lip (fig. 5) is rather delicate, broader than long, the extremity very slightly 

 emarginate and somewhat sparingly sujoplied with the usual incurving seta?. 



The mandibles (figs. 6, 7, 8, 9) closely resemble in general shape those of Niphargus, 

 as described by Humbert and other authors. The palp is rather large in proportion 

 to the mandible itself ; it lias the first joint small, the margins without seta? ; the second 

 joint rather broad, especially in the middle, where it is strongly curved, the convex 

 margin bearing about six or seven long setae, which project almost at right angles to the 

 joint; the third joint about as long as the second, outer margin nearly straight and 

 without setae, inner margin bearing on the distal half a double row of long setae, Avhich 

 increase in length towards the distal end. The palp is the same in both mandibles. 



The outer cutting-edge is practically the same in botli mandibles, and consists of five 

 teeth, the two largest of which are somewhat widely separated, the other three teeth are 

 smaller and subequal. In the right mandible (fig. 6) the secondary cutting-edge is very 

 similar to that of Nip>hargns puteanus, figured by Humbert, and resembles in shape an 

 open hand with the fingers close together ; the part corresponding to the thumb is denti- 

 culated throughout, while that corresponding to the fingers has the distal extremity 

 oblique and finely serrate. At the base of this secondary cutting-edge are two stout 

 spiniform setae denticulated similarly to the thumb, and following these is a stout plumose 

 seta (see fig. 7). 



The secondary cutting-edge of the right mandible usually has the form just described, 

 but it is evidently sul)ject to some variation, for in one specimen, which otherwise 

 appeared quite normal, it had the form rejiresented in fig. 8, which, it wdll be seen, 

 is very different from the usual form. Whether this was the result of accident or not I 

 cannot say, but it shows how careful one ought to be before laying much stress on the 

 form of tliese minute mouth-parts unless they are found to be constant by the examina- 

 tion of a large number of specimens. 



In the left mandible (fig. 9) the secondary cutting-edge resembles the outer cutting- 

 edge, and consists like it of five separate teeth ; at its base are stout denticulated setae 

 similar to those in the left mandible. It will be seen that this figure is inverted. 



The molar tubercle, which appears to be the same in both mandibles, is small and 

 presents no remarkable feature. 



The lower lip (fig. 10) is very delicate, broad ; extremity of each outer lobe very 

 broadly rounded and covered with fine seta? ; inner lobes small and very delicate ; the 

 lateral backAvard processes are short and rather ol)tuse. 



Thej^rs^ maxilla (figs. 11, 12, 13) is very similar to that of Niphargus puteanus. The 

 palp has the first joint short, its extremity oblique; the second joint slightly narrowing 



