CRUSTACEA 



301 



seen, is the maximum number of segments in the corm of the steno- 

 podium. The suggestion, made by this fact, that the segmentation of 

 the phyllopodium by endites corresponds with that which the corm 

 of the stenopodium owes to the presence of joints, is strengthened by 

 the fact that in some of the maxillae in question (Fig. 211 B), and in 

 that of Calanus (Fig. 240), which also has nine segments, the limb is 

 jointed and the joints fall between the endites or, where these are 

 lacking, precisely complete their number. A less regular jointing 

 of the same kind is present in some other phyllopodia (Apus^ Fig. 

 213 ; etc.). In both kinds of limb, also, the position of the exopodite 



Fig. 212. 



Fig. 213. 



Fig. 212. The second thoracic limb of Anaspides. After Caiman, with an 

 addition, en. endopodite; ep. epipodite; ex. exopodite; fix. flexure of limb; 

 I, position of precoxa or pleuropodite, represented, according to Hansen, by 

 an isolated area of chitinization of the thoracic wall ; 2, coxa or coxopodite ; 

 3, basis or basipodite (probasipodite) ; 4, preischium or metabasipodite ; 

 5, ischium or ischiopodite ; 6, merus or meropodite ; 7, carpus or carpopodite ; 

 8, propus or propodite; 9, dactylus or dactylopodite. 



Fig. 213. Tenth thoracic limb of Apus. br. branchia; jib. flabellum; gn. 

 gnathobase ; ep. epipodite ; ex. exopodite ; 1-5, segments of the limb ; z's', en- 

 dites ; 6, apical endite. 



bears the same relation to the segmentation, being usually upon the 

 third, occasionally upon the fourth segment, while epipodites stand 

 on the first or second segment. Endites are rare on stenopodia, 

 but a gnathobase is always present in the mandible (Fig. 211 D) 

 and sometimes in other limbs, and a few other such processes 

 occur. 



A limb of either type may differ from that type in the lack of any 

 of its parts. Notably the loss of the exopodite is liable to produce 

 from either a uniramous limb. Moreover, though the two types are 

 very distinct in cases in which they are perfectly developed, as in the 



