128 PKOCEEDINGS OP THE AMERICAN ACADEMY. 



Female. Chelae somewhat smaller than in the first form of the 

 male, fingers less widely separated at base, external finger ciliated at 

 base within. Anterior border of annulus ventralis nearly obliterated 

 in the median line, lateral borders raised into prominent tubercles, 

 transverse fossa wide. 



Length of body (male, form I.), 45 mm. Length of carapace, 

 22.5 mm. Length of areola, 8 mm. Breadth of areola, 2 mm. 



In the largest sjjecimen seen, the dimensions of which are given 

 above, the lateral sj^ines of the rostrum are obsolete, the margins 

 simply notched at base of the acumen ; in the other specimens the 

 lateral rostral spines, though small, are evident ; the antennae in the 

 larger specimens are shorter in proportion to the length of the body. 



Thirty-nine specimens (eighteen males, form I., two males, form IL, 

 and nineteen females) were collected by C. L. Herrick for the U. S. 

 National Museum in Second Creek, Waterloo, and in Cyprus Creek, 

 Lauderdale Co., Ala., October, 1882. 



A small species with first abdominal appendages of the male similar 

 to those of C. immunis. It is readily distinguished from all the other 

 species with similar male appendages by the lateral compression of the 

 cephalo-thorax, form of the chela, «fcc. 



17. C. Sanbornii, sp. nov. 

 Male, form I. Rostrum long, of moderate width, excavated, mar- 

 gins sub-parallel, lateral &\)mQ short, acute, brown-horny, acumen long, 

 triangular, acute. Post-orbital ridges sulcate without, vrith acute an- 

 terior spines ; carapace oval, flattened on the back, punctate, lightly 

 granulate and ciliate on the sides ; antero-lateral margin notched be- 

 hind the antennae ; cervical groove sinuate, interrupted on the sides 

 just above the small acute lateral spine ; areola of moderate width, 

 punctate, dilated anteriorly and posteriorly. Abdomen as long as 

 the body ; posterior border of telson rounded, posterior border of 

 basal segment bispinose on each side. Basal segment of antennule 

 armed with an acute spine on internal border of lower side, near the 

 apex. Antennae as long as the body, a small acute spine on the 

 external side of second segment ; scale a little longer than the ros- 

 trum, of moderate width, widest toward the middle, thence tapering 

 to the acute terminal external spine. Anterior process of epistoma 

 truncate in old specimens. Third pair of maxillipeds hairy within. 

 Chelipeds short, chela broad, punctate above and below, inner margin 

 with a double row of depressed squamous tubercles ; all the puncta 

 and tubercles of the hand give rise to pencils of fine downy cilia; 



