962 THE AMERICAN NATURALIST. [VoL. XXXIII. 
Sides of rostrum concave i C. diogenes ludovicianus Fax. 
Areola linear but not obliterated : ; . i À : . 16 
Areola obliterated in the middle Ž . ; ; ; ; S 
Rostrum short, slightly longer than bidad è C. carolinus Erich. 
Rostrum twice as long as broa ‘ C. mississippiensis Fax. 
Upper surface of rostrum plane and faintly carinate C. uhleri Fax. 
Upper surface of rostrum excavated, not carinate C. argillicola Fax. 
Rostrum with lateral teeth ‘ s ‘ i ; í -yk 
Rostrum without lateral teeth . : 63 
Sides of carapace with two spines nn behind the ceria groove . 20 
Sides of carapace with only one spine or unarmed . ; 21 
Proximal segment of telson with three or four spines on each side of 
the posterior border . . C. versutus Hag. 
Proximal segment of telson with dilya two spines 
C. spiculifer LeC. 
Rostrum with a more or less pronounced median longitudinal carina 
above à : : : i ; : . 22 
Rostrum without a carina ; . 29 
Proximal segment of telson with Sites spines on each side 
C. carinatus Fax. 
Proximal segment of telson with only two spines on each side . “as 
Sides of carapace with a spine ‘ . 24 
Sides of carapace unarmed. c. EEIE F ax. 
Outer finger of chela bearded at bae on inner margin 
Outer finger of chela not bearded . : n26 
Rostrum slightly excavated, carina biosd, ion: and sounded 
C. alabamensis Fax. 
Rostrum deeply excavated, carina very faint . : C. meeki Fax. 
Rostrum slightly excavated (broad and nearly plane above) 
C. neglectus Fax. 
Rostrum well excavated (narrower and deeply grooved) . ei 
Postorbital spine strong . : i C maihi Fat 
Postorbital spine weak . à : : ; i ‘ ; . 28 
Rostrum with a low carina. : : . C. propinguus Gir. 
Rostrum with a high, sharp carina . ; . C. digueti Bouv. 
Flagellum of antenna E flattened and heavily ciliate along the 
inner margin, ‘ : i . C. cornutus Fax. 
Flagellum of antenna orud. i Ioa : : 30 
Carapace without lateral spines . : : ; i ae 
Carapace with lateral spines š ; : ‘ i : ; 3g 
Sides of rostrum straight or concave ; : : : oe 
Sides of rostrum convex. i; : ; ` . 34 
Postorbital spines small or vaii ; . C. virilis Hag. 
Postorbital spines well developed ; ; : - 33 
Areola broader . : : ; i : > C rusticus Gir. 
