SCOHPIOKSOT? THE GENUS ISOMETRUS. 437 



the first segment with ten keels, the second, third, and fourth 

 with eight; the fifth with six keels, whereof the median inferior 

 is strongly developed and the superior lateral very feeble ; the 

 superior median excavation in the caudal segments, shallow on 

 the first, becomes progressively shallower from before backwards 

 and is almost absent on the fifth. Vesicle with a conspicuous 

 but very feebly granular inferior median keel and very faint 

 traces of a lateral keel on each side of it ; aculeus slender and 

 long, as long as the vesicle ; spine under the aculeus strongly 

 developed. 



Falp. — Humerus with upper surface very finely granular and 

 bounded in front and behind by a more coarsely granular ridge ; 

 anterior surface defined below by a feebly granular ridge and 

 bearing a few larger granules ; inferior surface smooth, posterior 

 surface smooth. B^^aclimm with three feebly granular keels on 

 its upper surface, a smooth weak keel on its posterior surface, a 

 few larger granules in front, and with smooth under surface. 

 Sand narrower than braehium, furnished above with two very 

 weak, very feebly granular keels, and in front with a few slightly 

 larger granules. Dactyli long, curved, in contact throughout 

 their extent, neither lobate nor sinuate. 



Legs. — GoxcB smooth ; femora granular in front, carinate and 

 granular above and below, smooth behind ; patellce granular 

 and carinate anteriorly ; tihicB also granular and carinate, those 

 of the tw^o posterior pairs armed distally beneath with a stout 

 spine. 



Pectines extending as far as, but not beyond, the distal extre- 

 mity of the coxse of the fourth pair of legs, furnished with 20-21 

 similar teeth and not provided with an internal basal lobe. 

 Stigmata slit -like. 



Measurements in millimetres. — Total length 62: cephalothorax, 

 length 7"5, width 7 ; tail, length 40, width at base 3'5, at posterior 

 end of 5th segment 25 ; 1st segment, length 4'5 ; 2nd segment, 

 length 5"5 (of the two together 10-5) ; 5th segment, length 8"3 ; 

 vesicle, length 4'5, width 2'4 ; aculeus, length 3. Palp — 

 humerus, length 7; braehium, length 8*5, width 3; hand, length 

 2*5; length of " hand-back " 4, of movable dactylus 8*5. 



A single specimen, in all probability a female, from Baram in 

 Borneo, collected by Mr. Charles Hose. 



Superficially this Scorpion bears a strong resemblance to the 

 females of the black American species I. americanus, 1. androcot- 



