LARVAL DECAPODS 41 



they possessed in the zoea, and have assumed their final form and 

 function. Identify all the mouth parts. 



Exercise 2, Draw a dorsal view of the animal, with the legs extended, 

 on a large scale. 



Mount several lobster larvae in the mysis stage and study them 

 under the microscope. The lobster is born in a more advanced 

 condition than is the crab. The zoea stage of the lobster is passed 

 through in the egg, and when the young animal emerges from the 

 egg it resembles Mysis, a schizopodous crustacean, and hence is 

 said to be in the mysis stage. The general form of the animal does 

 not differ much from that of the adult. The abdomen bears no ap- 

 pendages. The cephalothorax is very nearly like that of the adult 

 and bears the same appendages. The third maxilliped, however, 

 is a locomotory appendage, as it is in Mysis, and with the five 

 periopods is used for swimming. Notice the biramous character 

 of each periopod. 



Exercise 3. Draw a side view of the animal on a large scale. 



