NO. 1G59. AMERICAX i^I'ECJIJS OF tOXALrH EUS—rOUTlERPJ. 55 



is prolonged behind, and the very nniall carpus is inserted below 

 the principal axis of the ovoid palm. The lueropodite, the superior 

 border of Avhich ends in a riiiht ani>le, is 2. 2;") times longer than Avide. 

 In a comparison of the nude and female, the large claws are in about 

 the proportion of 1.3 to 1. 



The small claw is, to the large one, in the proportion of about 2.5 

 in the female, of 3 in the male, so that it is apparently of the same 

 size in both sexes; the relative dimensions are: Fingers 1; total 

 length 3; height about 0.8; T. L. :H.=3.75:1. The movable finger 

 bears two teeth, the lower of which is the stronger; the fixed finger 

 bears besides its point, two short angular prominences. 



The carpus shows some rather remarkable variations ; in the larger 

 specimens it is constantly longer than the palm; it is visually a little 

 shorter in medium or very small specimens of either sex. The total 

 length of the chela being taken for a unit, the length of- the carpus 

 may vary from 0.T4 to 0.50 and even 0.5; it is always shorter in the 

 female. In every case its distal width remains equal to that of 

 the chela. The meropodite is about 4 times as long as wide (4.4 in 

 the male, 3.6 in the female of large size). 



The second pair is notably stronger in the male (1.08), but of 

 similar proportions in both sexes; the first segment of the carpus is 

 shorter than the sum of the other 4 (proportion 1.2) ; the meropodite 

 equals twice the first carpal segment. The terminal claw is longer, 

 in the male, than the last 4 segments, but shorter in the female; it 

 bears, especially in the male, about ten tufts of hair. 



The third pair is also stronger in the male, where its relative dimen- 

 sions are : Meropodite 2.33, carpus 1, propodite 1.7; the mei-opodite is 

 3.5 times longer than wide. 



In the female these dimensions are : Meropodite 2.1, carpus 1, 

 propodite 1.55, the meropodite being 3.8 times longer than wide. The 

 ischiopodite is more slender and elongated also than in the male. The 

 dactyl is short, one-sixth or more of the propodite; the two hooks are 

 almost equal and divergent, the ventral normal to the lower border, a 

 little thicker at the base than the dorsal, becoming proportionately 

 longer in specimens of large size (female of 27 to 28 mm.) . The sixth 

 abdominal somite shows on either side of the telson a wide triangular 

 point. The pleopods of the fifth somite have a very short base and 

 a wide posterior expansion especially marked in the female, where it 

 contributes to close the incubatory cavity. The anus is shown imder 

 the telson between two very prominent swellings. All the abdominal 

 pleura of the male, even the second, end in a point. These last details 

 are more marked in the L.t:vimanus group than in any other, and es- 

 pecially in the two species S. loi^gicarpus and S. pectiniger. 



The telson has the following relative dimensions in the male: 

 Small base (distal) 1; large base (proximal) 1.7; height 2.3. In the 



