Mr. R. I. Pocock on Neotropical Scorpions. 83 



punctured both finely and coarsely ; manus not carinate, con- 

 vex above, its width a little greater than the length of the 

 hand-back, sculptured above with large and very fine punc- 

 tures whicli, towards the inner edge, pass into granules ; the 

 movable digit longer than the width of the hand ; a tooth on 

 the immovable as in Ch. amazonicus. 



Legs with minutely granular femora. 



Pectines short, with only six teeth. 



Measurements in millimetres. — Total length 52, of carapace 

 8'5, of tail 27 ; width of first segment 4, of second 3*5 ; length 

 of second 3*4, of fifth 8, width 3 ; width of vesicle 3'8, height 

 3 ; width of brachium 3, of hand 6+ ; length of hand-back 

 5"5, of movable digit 8. 



Two ? examples from Cuenca, in Ecuador {Fraser Coll.). 



Of all the known species of Chactas, IJeter-ochactas Gervaisii 

 comes nearest to Ch. Whymj^erij which has the anterior border 

 of the carapace conspicuously notched in the middle. 



Genus Chactas. 



The following is a synopsis of the species of this genus 

 that are known to me. (To be used with caution.) 



a. All the segments of the tail, including the first, 



furnished with the normal number of well- 

 developed gi-anulav keels ; the upper surface 

 of the trunk and the external siu-face of the 

 legs coarsely granular eequinoctialis (Karsch). 



b. The lower surface of at least the first caudal 



segment not fui-nished with gi'anular keels. 

 a\ The upper surface of the palpi and carapace 

 coarsely granular ; vesicle large, impressed 

 below ; brachium without an upper internal 

 basal tooth ; the proximal tooth on the im- 

 movable digit enlarged Whymperi, sp. n. 



b^. The legs nearly or quite smooth externally, 



the vesicle less globular and not impressed 



below. 



«^. The third and fourth caudal segments 



clearly carinate below, the second weakly 



carinate ; the carapace more coarsely 



granular at the sides ; the brachium with 



an enlarged tooth ; the immovable digit 



not basally dentate. 



a^. The upper surface of the abdomen finely 



and closely granular ; the caudal keels 



stronger Itevipea (Karsch). 



6'. The upper surface of the abdomen 

 smooth and polished ; the caudal keels 



weaker Simonii, ep. n. 



6*. The second and third caudal segments 



