378 CRUSTACEA. 



half wide. The hands are nearly equal and short. The outer maxil- 

 lipeds are naked, and the pterygostomian region hirsute. 



FAMILY V. PINNOTHERID.E. 



THE Pinnotheridae differ much in appearance, the form varying 

 from wide transverse, through orbicular, to oblong triangular, the 

 front becoming slightly rostrate in some species. In all, the sides are 

 rounded, and the male abdomen behind is much narrower than the 

 corresponding part of the sternum. They are often very much in- 

 flated and even subglobose, as in some Pinnotherae, or depressed, 

 with a flat thin body, as in the Hymenosoma. In Elamena, the third 

 joint of the outer maxillipeds is nearly as in many Grapsida?, smaller 

 than the second. But in Hymenicus, it is somewhat larger than the 

 second; in Hymenosoma, nearly twice as large; in Pinnotherelia, more 

 than twice, and in Pinnothera and related species, the second is 

 nearly obsolete. In the last-mentioned group, the outer maxillipeds 

 have usually a very oblique position, the two of the pair diverging 

 widely behind ; yet this is not invariable, and P. fdba, beyond, is an 

 example of near parallelism. 



The eyes in all are small, and in the species of Halicarcinus and 

 Hymenicus, although imbedded in orbits, they cannot be retracted and 



concealed. 



The species of this family naturally fall into two subfamilies. 

 These subfamilies and the included genera are distinguished as fol- 

 lows : 



1. PINNOTHERINJE. Articulus maxillipedis externi 2dus par- 

 vulus aut obsoletus. Corpus sive obesum sive depressum. 



1. Oculi approximati. Fossae antennales conjunctx. 



a. Pedes 8 postici sat graciles, subsequi. 

 G.I. PINNOTHERA, Latr. Corpus obesum. Carapax Buperficie integorrimus, 



nunquam areolatus. Oculi normales. 



G. 2. FABIA, Dana. Corpus obesum. Carapax superficie anticS. pone orbitas 

 sutura longitudinali divisus. Oculi normales. 



