112 PROCEEDINGS OF THE AMERICAN ACADEMY 



third and fourth pairs of legs are small tooth-like processes merely. 

 Besides the differences in these hooks and in the sexual appendages 

 the following may be pointed out : the rostrum has small lateral teeth 

 near the tip, the post-orbital ridges have a sharp spine at their anterior 

 end, the basal segment of the fifth pair of legs is armed with a sharp 

 hooked tooth in place of a flattened tubercle, and the hind segment of 

 the telson is longer in proportion to its width. 



§ 2. Third pair of legs of male hooked. First pair of abdominal 

 appendages of male as in § 1. 



4. C. SIMULANS, Sp. noV. 



Male, form I. Rostrum broad, deeply excavated ; margins raised 

 into sharp crests which overhang the base of the sides of the rostrum, 

 converging, sinuated before the tip to form the short acumen ; no 

 lateral spines ; the acumen is barely margined. Post-orbital ridges 

 subacute in front, divergent and ending in slight callosities behind. 

 Carapace ovate, narrowing in front, gastric area smooth, cardiac area 

 lightly punctate, sides granulate ; anterior border notched behind the 

 antennae ; cervical groove sinuate, split on the sides, with a minute 

 terminal branchiostegian spine; no lateral spine; areola more than one 

 half as long as the distance from the point of the rostrum to cervical 

 groove, narrow, carinate, expanding into an anterior and a jjosterior 

 triangular field ; two longitudinal dotted lines run along the areola from 

 the anterior triangle to the posterior triangle, which is irregularly and 

 sparsely dotted. Abdomen broad, shorter than carapace, punctate, pos- 

 terior margins of pleura obliquely convex ; hind margin of anterior seg- 

 ment of telson bi- to multi-denticulate on each side, posterior segment 

 short, hind border almost straight; median rib of inner plate of swim- 

 meret ends inside of the margin. Basal segment of antennule with a 

 spine below. Antenna; shorter than body, second and third segments 

 furnished with minute blunt spinules, scale a trifle longer than the ros- 

 trum, very broad, broadest in the middle, truncate at apex, external 

 terminal spine minute. Anterior process of the epistoraa triangular, 

 antero-lateral borders convex, rimmed, anterior angle truncate or 

 notched in old specimens, with a projecting median spine. Third 

 maxillipeds densely hairy within and beneath. Chela long, slender, 

 squamoso-tuberculate, internal margin long-, straight, strongly dentate ; 

 fingers long, punctate, external border of movable finger tubcrculate, 

 inner border of both fingers toothed, a prominent tubercle near the 

 base of external finger opposite a more or less clearly marked incision 



