SEA-FISIIERIES LABORATORY. 361 



The extensor {ex. ft.) is a short broad muscle 

 arising from the upturned edge of the sternum in this 

 somite. It passes outwards across the mouth of the cavity 

 of the coxopodite, and is inserted on the inner side of the 

 base of the flabellum. 



The anterior flexor (a.f.fl.) is a fairly broad muscle 

 arising from the posterior face of the last cephalic endo- 

 pleurite, immediately above the foramen of the latter. It 

 passes downwards, and is inserted on the anterior edge of 

 the base of the flabellum. 



The posterior flexor (p.f.fl.) is an extremely broad 

 muscle arising from the last cephalic endopleurite, above 

 the origin of the previous muscle. It runs downwards 

 behind the extensor of the coxopodite, and is inserted on 

 the posterior edge of the base of the flabellum. 



VIII. Second maxillipede. This appendage 

 is similar to the third maxillipede in structure, and its 

 muscles have the same arrangement (see below). 



The extensor muscle of the coxopodite arises from the 

 inner side of the second thoracic epimeron, and the flexor 

 arises from the upper end of the anterior face of the 

 second thoracic endosternite. All the muscles of the 

 basi-ischium are attached to the lower end of the anterior 

 face of the second thoracic endosternite. The muscles of 

 the flabellum are quite small, but have the same parts as 

 described in the first maxillipede. 



IX. Third maxillipede (fig. 30). 

 Coxopodite. There is a small extensor and a larger 



flexor. 



The extensor muscle arises on the inner side of the 

 third thoracic epimeron, and is inserted on the outer side 

 of the coxopodite by means of a narrow tendon (ex. C). 



The flexor muscle is attached to the anterior wall of 



