584 THE AMERICAN NATURALIST. [Vor. XXXIV. 
The Palicida, some of which appear in our list, are small 
anomalous forms, inhabitants, chiefly, of warm waters or of 
considerable depths. Four species are known to occur either 
in the Gulf or in the Cape Hatteras region in less than one 
hundred fathoms. 
TRIBE CATOMETOPA OR GRAPSOIDEA. 
Carapace broad anteriorly, often subquadrate, sometimes subglobose, 
truncate or arcuate anteriorly, but not rostrate. Front bent downward. 
Epistome short, often almost linear. The pairs of branchie are usually 
fewer than nine in number; the efferent channels open at the sides of the 
endostome. The male verges are inserted either in the sternal plastron, or 
in the basal joints of the last pair of legs, thence passing through channels 
in the sternum beneath the pleon. 
KEv TO THE FAMILIES OF THE TRIBE CATOMETOPA. 
A. Carapace hard and firm. Front, orbits and eyestalks not very small. 
Buccal frame quadrate anteriorly. 
B. Last pair of feet not remarkably reduced. 
C. Carapace moderately convex or depressed; branchial regions 
not greatly dilated. 
D. Third maxillipeds with the fifth joint articulated at the 
front inner angle usually. Front of moderate width 
or very narrow. Eyestalks often greatly elongate 
Ocypop1p# Leach 
D’. Third maxillipeds with fifth joint articulated at apex or 
ont outer angle of fourth. Front usually broad. 
Eyestalks of moderate size 
GRAPSID& Milne Edwards 
C. Carapace very convex, especially dilated over and in front of 
the branchial regions; antero-lateral margins entire or sub- 
entire, and strongly arcuate. Terminal joint of walking 
legs often armed with longitudinal rows of spines 
GECARCINIDE Milne Edwards 
B’. Last pair of feet remarkably reduced. . . Pavicip# Rathbun 
A’, Carapace often more or less membranaceous. Front, orbits and eye- 
stalks — very small Buccal frame arcuate anteriorly. Of 
small size . . . . . « PINNOTHERID Milne Edwards 
KEY TO THE GENERA OF THE FAMILY OCYPODIDÆ. 
A. Carapace trapezoidal or quadrate. Eyestalks often elongate. 
B. Lateral margins entire 
