!g6 ELEMENTARY BIOLOGY. [CHAP. 



multi-articulate segment ; the former however is 

 but a fourth the length of the whole. 



8. Examine under a low power, and note that the 

 calcifications of the multi-articulate segments 

 are incomplete; they are restricted to their 

 outer borders. Both exopodite and endopodite 

 will be found to be fringed with delicate setae. 



The above description applies equally to both 

 Lobster and Crayfish, except that in the former 

 animal the whole appendage is more foliaceous 

 and paddle-like. 



b. The second maxillipede (second appendage in 

 front of the great chela), as compared with a. 



a. Its protopodite; its two segments are short and 

 equal in size. The distal one furnishes the base 

 of articulation for both exopodite and endopo- 

 dite; the proximal one is prolonged out into a 

 delicate lamella or epipodite (not represented in" 

 a) which bears a well-defined gill. 



ft. Its endopodite. This now forms the main por- 

 tion of the whole limb, it is subdivided into 

 five segments; a basal ischiopodite ; an elongated 

 laterally compressed meropodite; a small carpo- 

 podite; an expanded propodite, and a short 

 terminal dactylopodite. The, inner edge of the 

 dactylopodite is beset by a series of sharp 

 spines; the rest of the endopodite is partly 

 fringed in sete. 



y. Its exopodite, long and filamentous; its structu- 

 ral features recall most nearly those of the 

 endopodite of the abdominal appendage. 



