REPORT ON THE CRUSTACEA MACRURA. 



229 



Pen^as, Fabricius. 



The body laterally compressed, particularly towards the postei'ior portion of the 

 animal. Carapace armed with a laterally compressed rostrum that is -more or less 

 dorsally serrated. 



The ophthalmopod is two-jointed, and the eyes are large and longitudinally ovate. 



The first pair of antennae has the first joint deeply excavate on the upper surface, and 

 furnished on the inner side with a prosartema, and on the outer with a sharp-pointed 

 stylocerite. It terminates in two flagella, and is never longer than the carapace. 



The second pair of antennae carries a large scaphocerite, rigid on the outer margin, 

 where it terminates in a sharp tooth, thin, foliaceous and fringed with long ciliated hairs 

 on the inner margin. The first joint carries a small phymacerite on the inner side, and 

 the third is furnished with a small hook (ancecerite) on the upper surface. 



The mandibles are strong and powerful, smooth on the psalisiform margin, furnished 

 with a flat, discoid, molar tubercle, and carry a large, foliaceous, two-jointed synaphipod. 



The first pair of siagnopoda is three-branched, the last or outer branch being 

 biarticulate, long, slender, cylindrical, and tapering. 



