No. 398.] WORTH-AMERICAN INVERTEBRATES. 139 
A’. Surface of carapace anteriorly nodose. Antero-lateral teeth strong, 
projecting well out from the carapace . M. nodifrons Stimpson S 
Genus Lobopilumnus A. Milne Edwards . . . Z. agassizii Stimpson G 
Genus Pilumnus Leach. 
Key to Species. 
4. Carapace concealed by a short, thick pubescence, which, when removed, 
discloses tubercles on the gastric and hepatic regions 
pannosus Rathbun G 
A’. Carapace, when covered by a short, thick pubescence, not having the 
gastric region tuberculate. 
B. Superior orbital border with one or few long spines. 
C. Superhepatic region unarmed 
P. spinohirsutus (Lockington) D 
C. Superhepatic region armed with spines or spinules 
P. sayi Rathbun M(CH)SG 
D, Superior orbital border either entire or armed with denticles or 
spinules. 
C. Outer surface of smaller hand only partially covered with 
tubercles or spines . P. lacteus Stimpson G 
C’, Outer surface of smaller bind entirely covered with tubercles 
orspnes . . . . . . + £&. floridanus Stimpson G 
KEY TO THE GENERA OF THE FAMILY PORTUNIDE. 
A. Last pair of legs broad, modified into swimming paddles, 
B. Carapace decidedly transverse; antero-lateral margins cut into 
nine teeth. 
. C. Movable portion of the antenna excluded from the orbital 
cavity by a prolongation of the basal joint of the antenna 
Charybdella 
C. Movable portion of the antenna not excluded from the orbit. 
D. No longitudinal ridge on the palate . . . . Arenæus 
D’. A longitudinal ridge on the palate. 
E. Abdomen of male L-shaped . . . . Callinectes 
E'. Abdomen of male triangular. . . . . Portunus 
B'. Carapace not very broad ; antero-lateral margins cut into five teeth. 
. C. Last tooth of antero-lateral margin developed into a spine, 
longer than the other teeth or spines . . - Bathynectes 
C'. All antero-lateral teeth similar . . 2. > Ovalipes 
A". Last pair of legs narrow, with dactylus Lisceobin . + + Carcinides 
THE SPECIES OF PORTUNID#. 
Genus Charybdella Rathbun . . . . . . C. rubra (Lamarck) S 
Genus Arenzus Dana TRES Uer A. cribrarius (Lamarck) MSG 
