166 Bulletin, Vanderhilt Marine Museum, Vol. II 



on the anterolateral margin, including the preorbital tooth; the first 

 four teeth are obtuse, triangulate, the next four are more acute, the 

 last two being especially sharp-tipped; the ninth or lateral tooth is 

 four or five times as long as the eighth tooth, very acuminate, pointing 

 direct outwards. The anterolateral margin is fringed with setae, 

 which show between the teeth. The postlateral margins are concave, 

 the posterior margin straight, with a light carina. The male abdom- 

 inal belt is five-segmented, triangulate, with the second segment much 

 the widest, sharply carinate transversely and forming an acute tip at 

 each distal end. The female belt is characteristically oval. An 

 average size female will carry 2000 to 3000 eggs at one time. 



The chelipeds are of moderate length, the extended merus reaching 

 out about as far as midway the lateral spine ; there are three, occasion- 

 ally four, acute, curved spines on the anterolateral margin of the 

 merus ; one sharp spine at the distal angle of the posterior margin ; 

 the carpus has a spine at the outer angle but none at the inner angle ; 

 the propodus has five longitudinal carinae; the fingers are grooved, 

 the cutting edges dentate, the tops curved. 



The ambulatories are very slender, the dactyli very acuminate, 

 longer than the related propodi ; the inferior lateral margin is fringed 

 with long setae. In life, these legs fasten hook-like around the 

 Sargassum weed. 



The natatory legs are remarkably strong and well developed; the 

 propodus and dactyl are both broad, oval. 



The external maxillipeds have the typical Poriunus formation, the 

 ischium rectangular, three-fourths as wide as long with a median 

 groove; the merus with the distal margin rounded, excavate for the 

 reception of the palp. 



The antennulae fold transversely beneath the frontal margin. 



The antennae are situated in the orbital sinus ; the basal article has 

 a node at its inferior distal angle; the remaining articles are succes- 

 sively smaller. 



The eye is large, reniform, shining black. 



Synonymy. — Fortunus pelagicus Bosc, Hist. Nat. des Crust., I, p. 220, 

 pi. 5, fig. 3 (part), 1802. 



Lupa pelagica Say, Journ. Acad. Nat. Sci. Phila., vol. 1, p. 97. — De- 

 Kay, Zool. N. Y. Crust., vol. VI, p. 11, pi. 6, fig. 8, 1844. 



Lupa sayi L. R. Gibbes, Proc. Amer. Assoc. Adv. Sci., p. 178, 1850. — 

 Dana, U. S. Explor. Exped., vol. 13, pt. 1, p. 273, pi. — , 1852.— 

 Stimpson, Proc. Phila. Acad. Nat. Sci., 1858, p. 38. 



