THORACIC AND HEAD APPENDAGES. 141 



i. The protopodite consists of coxopodite, bearing 

 a gill and coxopoditic setae ; and basipodite, 

 bearing endopodite and exopodite. 



ii. The endopodite consists of five segments, named 

 as in the legs. The first segment or ischio- 

 podite is the largest and is fused with the basi- 

 podite. 



iii. The exopodite is slender, and consists of a long 

 proximal segment and a distal many -jointed 

 filament. 



VII. The second maxillipede is smaller and less firmly 

 calcified than VIII., which it resembles in form ; 

 but the exopodite is larger than in VIII., and the 

 endopodite smaller, its largest segment being the 

 meropodite, and all its joints being movable. 



VI. The first maxillipede is smaller and softer than 

 VII. 



i. The two segments of the protopodite are expanded 

 on the inner side, forming a large two-lobed 

 lamella. A broad plate, the epipodite, takes 

 the place of a gill. 



ii. The endopodite is very small and two-jointed. 



iii. The exopodite resembles that of VII. 



3. The head appendages consist of three pairs of oral 

 appendag'es or jaws, V. to III., placed at the sides of 

 the mouth, and two pairs of pre-oral appendages, 

 II. and I., at the front of the head. 



V. The second maxilla consists of a protopodite, an 

 endopodite, and on the outer side an exopodite 



Fig. 33. — Astacus fluviatilis, var. nobilis. The oral appendages of the 

 right side seen from below and behind ; x 2J. (c. h. h.) 



Ill, the mandible. IV and V, the first and second maxillie. VI, VII 

 and VIII, the three maxillipedes. 



A, region of attacbmeiib to body-wall. AB and AD, points of insertion 

 of abductor and adductor muscles of mandible. B, basipodite. C, carpopodite. 

 GX, coxopodite. D, dactylopodite. E, epipodite. I', pivots of mandible. 

 G, gill. Hj coxopoditic setae. I, iscUiopodite, M, meropodite. W, endo- 

 podite. P, propodite. S, scaphognatliite. X, first segment of exopodite. 



