GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 169 



seventh, which is the most spiniform. The orbit has a strong tooth 

 at the outer and at the inner angle and one less prominent between ; 

 below the inner angle there is a narrow tooth more advanced than 

 those above. Frontal region, between the orbits, with a concave 

 dorsal surface ; anterior border cut into 4 teeth, those of the middle 

 pair nearer to each other than they are to those of the outer pair, and 

 separated by a shallower sinus; teeth of inner pair oblong, with 

 rounded end; those of outer pair thicker. Postero-lateral margins 

 nearly straight; posterior margin slightly convex and thickened. 



Surface covered with a pavement of fine, flattened granules, and 

 with less numerous and unequal punctae visible to the naked eye. 

 The depression between the gastric and branchial regions is well 

 marked except anteriorly, the hepatic region not being defined. 

 Genital region very narrow, longer than wide. Cardiac and intestinal 

 regions incompletely outlined. 



Neither the eyes nor the antennae are visible. 



Epistome subtriangular, prolonged downward t the middle in an 

 acute angle; thence a small button-hole groove runs obliquely back- 

 ward. Palatal ridge strong except anteriorly where it is low and 

 blunt. Pterygostomian region granulate, densely so near the buccal 

 cavity. On the sternum a furrow runs obliquely forward from the 

 coxae of the chelipeds to the median line. 



The abdomen of the male is broad and at the base reaches to the 

 coxae of the last pair of feet; there is only one segment visible be- 

 tween the carapace and the third segment; it is probably the second, 

 while the first is hidden under the carapace much as in the Portunid 

 genus Callinectes; the second is of nearly even length throughout 

 its width ; the third, fourth and fifth are fused, but their extent is 

 indicated by indentations in the lateral margins and by a short groove 

 at the middle; the 3d segment is produced sideways beyond the 

 2d and 4th and its margins are very convex; margins of the 4th to 

 6th segments, inclusive, taken together are slightly convergent, those 

 of the 4th a little convex; 6th segment about If times as wide as long; 

 terminal segment nearly as long as the preceding, subtriangular, end 

 rounded. 



Chelipeds very stout, in general smooth, there being no ridges nor 

 spines. The surface is finely granulate and punctate, the granules 

 a little higher than on the carapace. The inferior, anterior margin 

 is the only margin of the merus visible; it is smoothly rounded. 

 Carpus massive, with a broad tooth at inner angle. Chelae unequal, 

 thick, broadly rounded above and below without marginal lines; 

 right or larger manus about 1 times as long as high, left or smaller 

 manus about 1 times as long as high; next the articulation of the 

 larger palm with the dactylus there is a large lobe or tooth directed 

 toward the end of the dactylus, as in Scylla. The digits each have 2 



