270 MARINE INVERTEBRATES 



GENUS Petrolisthes 



_P. sexspinosus. Carapace longer than broad; breadth about one 

 half of an inch ; space between the eyes broad, but not divided into 

 three teeth as in Parcellana sayana ; second joint of the cheliped has 

 five broad teeth on its front edge and five or six small spines on its 

 outer edge ; fifth pair of legs doubled over base of carapace ; whole 

 body traversed with broken red lines. Found from South Carolina 

 southward. (Plate LXI.) 



_P. armatus. Carapace longer than broad ; breadth about one quai 

 ter of an inch ; prominent and wide between the eyes ; a small sharp 

 spine on each anterior side ; chelipeds long ; second joint of cheliped 

 twice as long as broad, with three teeth on the front edge and four or 

 five small spines on the outer edge. Found on the Florida coast. 

 (Plate LXI.) 



FAMILY LTTHODIDJE 



The species of this family have a broad, ovate, uneven body 

 and a prominent rostrum. The fifth pair of legs are rudimentary 

 and are folded under the carapace in the branchial chambers, so 

 that the crabs appear to have but four legs on each side. This is 

 the distinguishing feature of the family, and makes them easily 

 recognized. 



GENUS Lithodes 



L. maia. The carapace is cordate (heart-shaped), and longer than 

 broad, exclusive of the rostrum. The margin is recurved all around, 

 and is beset with numerous very long spines. Six spines on each 

 anterior side margin are regular and longer than the others. The sur- 

 face of the carapace is covered with tubercles and spines and elevated 

 in places. The rostrum is spiny, a third as long as the carapace, and 

 has two spines at the base, one above the other, a spine at each side, 

 two lateral spines near the middle, and two terminal divergent spines. 

 The chelipeds are unequal and are covered with spines, those on the 

 inner margin being the longer. The color is yellowish-red, lighter 

 underneath ; the spines are darker. Found on the fishing-banks off the 

 coast of Maine. (Plate LXI. ) 



GENUS JEchidnocerus 



E. cibarlus. This curious crab has the carapace raised in front into 

 a large cone-like elevation terminating in a long point. Three promi- 

 nent but smaller cones extend across the center of the back, and two still 

 smaller ones occur on the posterior sides and in the middle of the poste- 

 rior margin. The whole surface of the carapace is covered with coarse 

 granulations arranged in rosette-like groups. The chelipeds and legs are 

 beset with large tubercles and fold together in such a manner that when 

 retracted the crab is a close, compact, box-like mass, with a very rough, 



