SALrA. 



dorsal (Fig. 1), or from the ventral side (Fig. 2), is barrel-sliaped, 

 with a iiniforni curvature at botli ends. The posterior exti'eniity 



Fig. 351. 

 (Fig. 2.) 



Fig. 352. 



(Fi'T .3.) 



p.p. 



p.p 



