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 posterior 

 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. Antennas 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 epistoma triangular, 

 anterolateral 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 tuberculate, 

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

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



