FRESHWATER CRABS OF AMERICA— RATRBUN. 



521 



TVpe.— One female, ^o. 18818, U. S. N. M. Near La Ouayra, Vene- 

 zuela; Lieut. Wirt Eobinson, United States Navy, June 23, 1895. 



Additional specimens. — Caracas; Gollmer (No. 375, Berlin Mus., one 

 male; Nos. 378, 384, 385, three females), Venezuela; E. Simon (Paris 

 Mus., one male and four females). 'Antilles' (Kiel Mus., three males). 



Of the habitat of this species, Lieut. liobiuson says: 



About three-fourths of a mile to the eastward of La Guayra a bed of a stream 

 euters the sea. Ascending the valley, or rather canyon, down which this bed 

 runs, there is on the right liand side an acequia, or aqueduct, cut out in the face 

 of the steep hills. This taps the stream a mile above and takes all of its water leav- 

 ing the bed from this point dry. About three-fourths of a mile back from the sea 

 the canyon grows deeper and narrower and is filled with large buttressed trees. 

 The little acequia winds among these in a semigloom. All .ilong under the roots 

 of these trees and under loose stones to tlie right and left, these little whitish crabs 

 have burrows and sit at the entrance of them, gliding 

 back under shelter as one passes near. 



PSEUDOTHELPHUSA DILATATA, new species. 



Superior margin of front tuherculate, not keeled; 

 loiver margin convex; cervical suture sinuous; me- 

 rus ofmaxilliped toith outer margin convex ; exog- 

 nath about half length of ischium. 



Closely allied to F. xantusi. Carapace of sim- 

 ilar proportions, with large puncta;, but devoid 

 of the granulation so conspicuous on the fron- 

 tal and lateral regions of P. xantusi. Cervical 

 suture sinuous and deep, very broad in its inner 

 half. 



Branchial region very convex anteriorly, as in 

 P. xantusi. Median furrow continued to the 



lower margin of the front. Front narrower than in xantusi; lower mar- 

 gin arcuate, most depressed in its central portion (fig. 12, a); in xantusi 

 this margin for its entire length is in almost the same horizontal i)lane; 

 upper margin also arcuate; front slightly deeper toward the outside. 

 Orbits differing from those of xantusi; in the latter the upper and 

 lower margins are regularly arcuate; in dilatata the orbits are sub- 

 quadrilateral, the side margin of the front forms somewhat of an angle 

 with the upper margin which is nearly straight for a ways; the lower 

 margin beginning at the inner end slopes outward and downward. 

 Maxillipeds similar to those of xantusi (fig. 12, h). The abdominal 

 a[)pendages of the male are akin to those of jouyi and americana; the 

 outer laminate branch near the extremity is wider distally than proxi- 

 mally; more spreading than in jouyi and is 3-toothed; the inner pro- 

 jection is a broad, rounded lobe with a small tooth above its base (fig. 

 12, e,f). The chelipeds are very unequal in both sexes, but more so 

 in the male. The palm in the larger cheliped widens considerably 

 toward the fingers and is very thick and heavy, its lower margin con- 



FlG. 12.— PSEUDOTHEI.PHUSA 

 Dn.AT ATA, MALE. «. FUONT, 



X f . b. Maxilliped, X IJ. 



c. Laroee chela, X i. 



d. Abdomen, x f. e. Left 



ABDOMINAL APPENDAGE, 



LOWER VIEW, x 2. /. The 



SAME, INNER VIEW, X 2. 



