collected by Mr. J. J. Walker, 245 



tlian to those in Keyserling's collection ; for, as may clearly be 

 scon from the figure given by this autlior, the keel on the 

 upper surface of the hand is very feebly developed. 



1 propose to call this species U. Keyserlingu^ in honour of 

 the late eminent arachnologist. 



This new species is most closely allied to U. abruptus, 

 Pocock, and may prove to be identical with it. The hands, 

 however, are much less strongly keeled. 



lODACUS, gen. nov. 



Cephalotkorax with ante-ocular portion flat and anterior 

 margin widely excavated ; median eyes in the middle of the 

 ccphalothorax, the tubercle cleft j lateral eyes two, above the 

 border of the cephalothorax. 



Sternum pentagonal, as long as wide, with sides sub- 

 parallel, perhaps very slightly converging anteriorly. 



Tail weak, furnished below with a single median keel, 

 exactly as in Urodacus, without a spine beneath the aculeus. 



Cheliceroi with lower borders of digits unarmed ; apex of 

 movable digit simple, undivided. 



CheUe with hands flat, almost as in Euscorpius ; the 

 proximal half of the digits furuished with many small sub- 

 equal denticles, irregularly arranged in three rows j the distal 

 end with a median series of denticles and an external and 

 internal series formed of transversely set denticles. 



This new genus is closely related to Urodacusj Peters, as is 

 shown by the presence of a median keel on the lower surface 

 of the caudal segments &c. It differs, however, in the shape 

 of the sternum, which is as long as wide, and in having the 

 upper surface of the manus flattened. In Urodacus the 

 sternum is considerably wider than long and the hand is 

 convex above. It is probably also related to loctonus — a 

 genus unknown to me ; but it certainly differs in the keeling 

 of the tail and in the form of the sternum *. 



lodacus Darwiniij sp. n. (Plate XIII. B.) 

 Colour (in alcohol) pale ochraceous or testaceous throughout. 

 Cephalothorax perfectly smooth, very sparsely punctui'ed 

 and hairy, narrowed anteriorly, its posterior width greater 



* The sternum in Io-)tonus is presumably wider than long-. In his 

 description, however, of /. municatus Dr. Thorell (p. 263) sa3^s: — ^'Sternum 

 diqilo fere lonyius quain latius ; " whereas of the following species, /. 

 orthurus (p. 265), he remarks, ^^Stenium multo latius quam longius" If 

 these descriptions be exact the two species can scarcely be congeneric. 

 But there can, I think, be little doubt that in the case of /. mnnicatiis the 

 words longius and latius have become transposed ; for uo scorpion to my 

 knowledge has the sternum nearly twice as long as wide. 



