126 PROCEEDINGS OF THE AMERICAN ACADEMY 



hardly developed. Carapace smooth, punctate, cervical groove sinuate, 

 with minute lateral and branchiostegal spines ; anterior margin notched 

 at base^f antennae ; areola wide, short (less than one half as long as 

 the distance from cervical groove to the lateral rostral spines), thickly 

 punctate. Abdomen longer than the cephalo-thorax by the length of 

 the terminal segment of telson. Telson rounded behind, basal segment 

 bispinous. Epistoma triangular. Antennaa nearly as long as the 

 body, slender ; scale moderately broad, broadest in middle, thence ta- 

 pering to the apical spine. Third maxillipeds hairy within and below. 

 Chelipeds of moderate length, strong. Chela broad, thick, hand 

 punctate, inner margin of moderate length, scarcely serrate ; fingers of 

 moderate length, costate, ciliate-punctate, usually meeting only through 

 their distal third. Immovable finger heavily bearded at base within, 

 both above and below. Carpus smooth, punctate above ; on the in- 

 ternal border there is a strong median spine, in front of this near the 

 articulation is a minute spine, and behind it are one or two faint 

 ones near the base ; below, the carpus has a single small spine 

 near the external articular point of the hand. Meros smooth, punc- 

 tate, two obliquely-disposed spines near the anterior end of superior 

 border ; of the biserial spines beneath, only the distal one or two of 

 the outer row are developed. Third pair of legs hooked at base. First 

 pair of abdominal appendages long, deeply bifid, rami slender, recurved, 

 parallel, inner ramus spoon-shaped at tip, outer ramus a little longer 

 than the inner, compressed laterally, tapering to a fine point at tip. 



Male, form II. Lateral rostral spines a little more prominent, hand 

 smaller, hooks on third legs less strongly developed, first abdominal 

 appendages thicker, bifid for only a short distance from the tip, rami 

 laterally compressed, blunt-pointed. 



Female. Rostrum as in the second form of the male, hand shorter 

 and wider. Annulus ventralis with well-marked trauverse fossa. 



Measurements of a male, form I. : — Length, 55 mm. Carapace, 

 25 mm. Abdomen, 30 mm. Length of antennte, 50 mm. Length of 

 areola, 7 mm. Breadth of areola, 2.5 mm. Length of chela, 21 mm. 

 Breadth of chela, 9 mm. Length of movable finger, 12.5 mm. 



A female of the same size lias the areola 3 mm. in width, 7 mm. 

 in length. 



Forty specimens, including both forms of the male and the female, 

 were collected by C. L. Herrick in Second Creek, Waterloo, Lauder- 

 dale Co., Ala., for the U. S. National Museum. The male appendages 

 are very like those of C. Mississippiensis, the rami being longer and less 

 strongly recurved than in C. immnnis. It is at once distinguished by 



