80 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



carpus,' it is also shorter than the antenniile, especially in the fe- 

 males, while in /S. longicarpus it is always longer. 



The carpocerite surpasses the antennule by two-thirds or only one- 

 half of the distal article ; it is cylindrical, a little concave on the out- 

 side, and 6.8 times as long as wide. 



In the males the proportions of the large chela are : Movable finger 

 1 ; total length 3.5 ; height 1.2. The anterior margin of the palm 

 bears a strong, sharp-pointed, conical prominence directed obliquely 

 upward. The movable finger is out of the perpendicular for at 

 least half of its length, the inferior margin of the palm rising ab- 

 ruptly in the place of the fixed finger, which is unprovided with any 

 point and serves only to receive in its cavity the inferior processes 

 of the opposing finger. 



In the females, with the same general form, the large chela is much 

 more slender, its proportions becoming: Movable finger 1; total 

 length 5; height 1.3. The superior margin of the meropodite is a 

 little convex, terminating in a right angle. 



The proportion of the large chelse in the two sexes is about 1 : 1.7. 



In the male the proportions of the small chela are : Fingers 1 ; 

 total length 2.58 ; height 0.88. The carpus measures 0.62 of the total 

 length. The meropodite is 3.8 times longer than wide. 



In the female the proportions become 1, 3.2, 1.1, the fingers being 

 shorter. The carpus measures only 0.56 of the total length, and the 

 meropodite is 3.3 times longer than wide. The proportion of the 

 small chelae in the two sexes is hardly 1 : 1.06. 



This appendage is quite characteristic of the species : In both sexes 

 each of the fingers is terminated by a plate divided into three curved 

 and obtuse teeth ; on the movable finger, which appears truncated, the 

 teeth are equal and more and more inclined downward; on the fixed 

 finger the innermost tooth is reduced to an obtuse prominence. As 

 the teeth cross each other Avhen the chela is closed, they constitute an 

 effective implement for dividing the prey. 



The proportions of the second pair are: First segment of the 

 carpus 1 ; sum of the four following 1.3 ; chela 1.15. The proportions 

 are the same in the two sexes, the entire member being more robust in 

 the female. The meropodite measures 0.0 of the carpus. 



The proportions of the third pair are : Meropodite 2.5 ; carpus 1 ; 

 propodite 1.64. The meropodite is 4.3 times longer than wide. In 

 the female these proportions become 2.2, 1, 1.5, and the meropodite is 

 a little less thick (4.1). The" dactyl has two hooks directed in the 

 same plane as the inferior border, at least in the case of the dorsal 

 hook, which is longer and stronger than the ventral. 



All the abdominal pleura, in the male, terminate in a strong tri- 

 angular point; even the second and the sixth pleosomite are pro- 

 longed in two strong spines on both sides of the base of the telson. 



