28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 92 



7p. Musculus flagellaris exopoditis I pedis fnaxillaris (fig. 9). — 

 Originating in the proximal segment of the enlarged first joint of the 

 flagellum, this muscle runs outward through the various segments 

 nearly to the tip of the flagellum, giving off small fibers in each seg- 

 ment which attach themselves to the wall, thus giving a high degree 

 of pliability to the flagellum. 



THE SECOND MAXILLIPED 



In this appendage the first true hinges between the segments appear, 

 just as they do in both Astacus and Pandalus. In section, the ischio- 

 podite is found to be fused with the basipodite. The exopodite is 

 merely an annulated flagellum as in Pandalus. The promotor appears 

 to be inserted by a tendon, as are some of the muscles at the distal 

 segments of the endopodite. A long, flat epipodite and two podo- 

 branchiae are present, with a slender attractor muscle to control the 

 epipodite. In Astacus there are two podobranchiae and no epipodite ; 

 in Pandalus, a single podobranchia and an epipodite are present. 



80. Muscidus promotor II pedis maxillaris (fig. 10). — This muscle 

 arises usually in two parts on the inner median edge of the paraphragm 

 between the first and second thoracic segments in a very broad attach- 

 ment. The muscle fibers rapidly converge into a single thin tendon, 

 which is attached to the extreme inner edge of the coxopodite. It 

 causes the entire endopodite to move inward and upward. 



81. Muscxdus rcmotor II pedis fiMxillaris (fig. 10). — This muscle 

 arises on a more lateral part of the two paraphragms next to the 

 gill-chamber, and proceeds forward and inward to its insertion on the 

 outer posterior border of the coxopodite. It lowers the outer part of 

 the coxopodite, bringing it distinctly outward and backward. 



82. Muscidus levator II pedis maxillaris (fig. 10.) — This muscle 

 arises as a heavy and massive muscle on the inner lateral edge of the 

 paraphragm between the first and second thoracic segments, and passes 

 without diminution in size to its insertion on the dorsal proximal 

 membranous portion of the basi-ischiopodite. There is but one levator 

 in Callincctes; both Astacus and Pandalus have two. 



5j a, h. Musculus depressor a and h II pedis maxillaris (fig. 

 10). — The main branch of the depressor arises on the inner edge of 

 the paraphragm between the first and second thoracic segments mid- 

 way between the origins of promotor and levator. It parallels these 

 two muscles to its insertion on the inner posterior border of the coxo- 

 podite. It gives a strong inward and downward pull to the coxopodite 

 and hence to the whole of the endopodite. The small depressor b arises 



