28 INVERTEBRATE ZOOLOGY 



Exercise 12. The two pairs of delicate appendages in front of 

 the maxillipeds are the maxillas ; they are cephalic append- 

 ages. Remove with forceps the right-hand second maxilla 

 and draw a large outline of it. The protopodite is wide 

 and leaf-like ; the endopodite is small ; the exopodite is 

 wide and with the epipodite forms a broad plate, called the 

 scaphognathite, which is used by the animal to maintain a 

 current of water from the gill-chamber. 



Exercise 13. Remove carefully and draw the right-hand first 

 maxilla. The protopodite is wide and leaf -like and similar 

 to that of the second maxilla ; the endopodite is extremely 

 small ; the exopodite is wanting. 



Exercise 14. Extract with strong forceps and draw the right- 

 hand mandible. The biting portion of it, together with 

 the first joint of the small palp, forms the protopodite ; the 

 two terminal joints of the palp are the endopodite; the 

 exopodite is wanting. Close to the posterior surface of 

 the mandibles are the delicate paragnatha. 



Exercise 15. Remove at its base and draw the right-hand second 

 (the longer) antenna. The exopodite is a short, stiff, plate- 

 like expansion ; the endopodite is the long slender terminal 

 portion. 



Exercise 16. Remove and draw the right-hand first antenna, or 

 antennule as it is also called. No exopodite and endopo- 

 dite are present in this appendage throughout the Crustacea, 

 there being but one terminal branch. In the crayfish and 

 lobster this terminal branch is double. 



Exercise 17. Construct in your notebook a table showing the 

 relation of the appendages and somites, as follows: 



