OF ARTS AND SCIENCES. 131 



groove. Between the ridge and the sternal plates of the fourth pair 

 of legs there is a deep transverse fossa. 



Measurements of a male, form I. : — Length of body, 60 mm. 

 Length of carapace, 30 mm. Length of abdomen, 30 mra. From 

 end of rostrum to cervical suture, 20 mm. From cervical suture tj 

 posterior border of carapace, 10 mm. Length of rostrum, 10 mm. 

 Breadth of rostrum at base, 4 mra. Length of rostral acumen, 3 mm. 

 Width of areola, 1.5 mra. Length of antennte, 60 mm. Length of 

 cliela, 25 mra. Breadth of chela, 12 mm. Length of movable finger, 

 17 mm. Internal border of hand, 7 mm. 



In one specimen, a male, form I., the fingers are very much elon- 

 gated, not gaping at base. The length of the internal border of the 

 hand in this specimen is 7.5 mm. ; the length of the movable finger, 

 21 mm. 



Irondale, Mo. Collected by E. Harrison. 



This species resembles C. rusticus in its general form. The male 

 appendages, as well as the annulus ventralis of the female, however, 

 are very different from those of any previously described species. 

 The male appendages ajjproach in form those of C. py-opinqiais more 

 nearly than any other, but in that species these appendages are more 

 deeply bifid, and not recurved. 



The second form of the male is unknown. 



19. C. Pdtnamt, sp. nov. 



Male, form I. Rostrum broad, sub-excavated, margins nearly par- 

 allel, with a line of ciliated puncta ; acumen long, equal in length to 

 the width of base of rostrum, narrow, acute, with a black, horny tip 

 and lateral spines. Post-orbital ridges sulcate on external side, in- 

 flated at posterior end, armed with a sharp, horny-tipped anterior 

 spine. Carapace long-oval, slightly flattened above, heavily punctated 

 sides rough with ciliated granules ; cervical groove deep, lightly sinu- 

 ate, broken on the sides just above the small, acute lateral spine ; 

 branchiostegian spine slightly developed; anterior lateral margins an- 

 guhited, but without sub-orbital spine. Posterior segment of carapace 

 equal in length to one half the distance from tip of rostrum to cervical 

 groove. Areola of moderate width, punctated. Abdomen as long as 

 cephalo-thorax, pleural punctate, telson bispinose on each side. An- 

 terior process of cpistoma ciliated, triangular, sides convex, margin- 

 ated. Basal segment of antennule armed below with an internal 

 ante-apical spine. Antenna? slender, about as long as the body, scale 

 as long as the rostrum, of moderate width, external border inflated, 



