170 
CLASS CRUSTACEA. 
body is convex, and the feet are very long. But a single spe- 
cies is known. Maia longipes , Coll, du Mus. 
If we except some species of hymenosoma , in which the tail 
presents distinctly but four or five articulations, in all the fol- 
lowing subgenera this part of the body has six, either in both 
sexes or in the males. The third articulation of the external 
jaw-feet is sometimes in the form of a reversed triangle, or of 
an oval, narrowed inferiorly, sometimes in the form of a heart. 
The following articulation is inserted at the middle ol its 
superior edge, or more externally than internally. 
Some, such as the three following subgenera, approach to 
those which we have just described, in the isometrical, or at 
least transverse form of the epistoma. The basis of the inter- 
mediate antenna) is but little remote from the upper edge of the 
buccal cavity. 
One of these subgenera is distinguished from the two others 
by the flatness of its testa, and by the upper extremity of the 
first articulation of its lateral antenna) (free in many), not ex- 
ceeding that of the ocular|pedicles. Such are 
Hymenosoma, Leach. 
The testa is triangular or orbicular. ( Fhymenosoma orbica- 
laria , Desm.) 
In the two following subgenera the testa is more or less 
convex, always triangular, and terminated in front in the man- 
ner of a bill. The first articulation of the lateral antenna), al- 
ways fixed, forms a crest, or projecting line, between the 
fossets of the middle antennm and those of the eyes, and which 
is prolonged beyond the end of the ocular pedicles. 
Inacpius, Fab ., 
Have six segments in the tail ; all the tarsi almost straight, or 
