394 STALK-EYED CRUSTACEA 



is serrated. The spine on the anterior edge and distal 

 end of the fourth joint is present on the second and third 

 pair of legs, but not on the fourth pair. 



Range. — St. Thomas, Bermuda, Aspinal, Florida. 



3. Petrolisthes marginatus. 



PetrolistJies marginatus .... Stimpson. 



Resembles Petrolisthes arniatus^ but the median lobe 

 of the front is smaller and more promi'nent, and the fifth 

 joint shorter. There are four teeth, equal in size and very 

 sharp, on the anterior margin of the carpus of the left first 

 leg. The surface is smooth and pubescent. The hands 

 are granulated, and covered above with a very short but 

 dense pubescence. From the inner base of the finger 

 to the exterior angle of the fifth joint there extends a 

 moderately prominent ridge. The anterior margin of the 

 hand is regularly crenulated, the tubercles being of a 

 lighter colour than the rest of the hand ; beneath these are 

 two rows of marginal granules. The fourth joint of the 

 walking legs is spinulose above, and one-spined below, 

 near extremity. Colour a purple-crimson. 



Range. — Barbados. 



4. Petrolisthes tridentatus. 



PetrolistJies tridentatus . . . Stimpson. 



Carapace smooth and unarmed. Front deflexed and 

 tridentate, with the median tooth or lobe triangular ; 

 margins smooth. The teeth of the front are most 

 distinctly seen in a front view. Feet nearly naked. First 

 pair of legs scaly; fifth joint about twice as long as 

 broad, with the anterior margin nearly straight, not 

 toothed, very slightly projecting at the inner angle. The 



