i86 



THE CRUSTACEA 



endites present a close approximation to those of Tanaidacea and 

 Isopoda. In Campylaspis the endites are suppressed. 



The first thoracic appendages 

 with their respiratory epipodites 

 (Fig. 115) have a close resem- 

 blance to those of the Tanaidacea, 

 in which group, however, there 

 is no exopodite. The basipodite 

 has an endite directed distally, 

 and carries on its inner edge 

 two or three hooked spines 

 FIO. in. ("coupling-hooks") which inter- 



A, maxlllula, B, maxilla, of Diastylis Goodsiri. lock with those of the Other side. 



1-4, segments of the appendages ; H-H, endites mi i i ,1 i ,1 



of the respective segments; /, flabellmn (ex- Ine SCCOnd and third thoracic 



opodite) ; p, palp. According to Hansen's later limVvj tVmno-Vi IPQO crppinli<jprl 



interpretation.the chitinous piece here numbered limDs > thOUgh 16SS SpeCiallSOU, 



4 in the maxilla does not represent a distinct may also be reckoned as maxilli- 

 segment, and the endites 1 3 and 1 4 result from r , ,. 



the division of a single endite belonging to the peds, SlllCO they are turned I0r- 



wards and applied to the oral 



region with their basipodites flattened and meeting in the middle 

 line, while the terminal segments are relatively 

 weak and carried in a folded position. The 

 second pair are without exopodites, but in the 

 female a small scale bearing a fan-like fringe 

 of setae is attached behind to the base of the 

 limb, projecting backwards into the marsupial 

 chamber and serving to keep in motion the 

 eggs or embryos contained therein. This scale 

 is doubtless homologous with the oostegites, 

 which are well developed on the four succeed- 

 ing pairs of limbs, where they are firmly 

 attached to the small coxal segments. The 

 third pair are only rarely devoid of exopodites. 

 The fourth pair of thoracic limbs are long 

 raptorial or prehensile leys (Fig. Ill, I 1 ), 

 though their broad basipodites, sometimes 

 meeting in the middle line, are not dissimilar 

 to those of the preceding pair. The fifth pair 

 (2nd legs) often have a reduced number of FIG. us. 



joints and differ in details from the succeed- First maxiiiiped of Dia- 



.1 1-1 n M i stylis stygia. bs, basipodite ; 



ing three pairs, which are all similar and appear br, branchial lamellae on 

 to be fossorial in function. The small terminal ^^^{t7Vr?S2pcSite, ; 

 segment in these limbs is tipped with a com- Arming the 'respiratory 



, . siphon. (After Sars.) 



paratively weak spine, which only in the 

 Nannastacidae becomes a stout curved claw. Natatory exopodites 

 are always present on the fourth pair (1st legs), and usually on 

 one or more of the succeeding pairs in the female sex; in the 



