300 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 1892. 



pectinal teeth. These characters by themselves, however, would 

 hardly justify the formation of a new species; but when they are 

 correlated with a marked difference in the shape of the hand in the 

 adult male, their value is of course enormously enhanced. In the 

 adult male of maculatus — a cosmopolitan species of which I have seen 

 very many examples from almost all tropical and sub-tropical 

 regions — the width of the hand is about equal to the width of the 

 brachium or fore-arm, is about one-third the length of the hand-back, 

 i.e., the area between the joint of the movable dactylus and the joint 

 of the wrist, and about one-quarter the length of the movable dactylus . 

 Whereas, as stated above, in the single adult male of /. thurstoni from 

 the Sheveroy Hills the hand is much thicker than the brachium (cf. 

 measurements), its width is equal to half the length of the hand-back, 

 and considerably more than a third the length of the movable dactylus. 

 In addition to /. maculatus this species is closely related to a 

 second Indian species of the genus, namely /. assamensis, described 

 and figured bj^ Mr. Gates in his paper in this Journal, which has 

 been previously mentioned. The three species in fact agree in the 

 entire absence of a spur on the apex of the proximal segment of the 

 tibia of the 3rd and 4th pairs of legs. I. assamensis, however, in 

 addition to two other characters to which Mr. Gates has referred, may 

 be recognized from both those here discussed by the presence of only 

 two, instead of four, granular keels on the last abdominal sternite. 



(2) Isometrus (ArchisometrusJ scaler, sp. n. 



Colour* ; cephalothorax obscurely ochraceous, very indistinctly 

 variegated with fuscous, the lateral margin and the ante-ocular 

 portion fuscous, the ocular tubercle and the eyes black; tergites 

 obscurely variegated, with two indistinct posterior yellow spots and 

 an anterior -shaped yellow mark on each side ; palpi and legs ochra- 

 ceous, very indistinctly clouded with darker patches ; tail, like the legs 

 nearly concolorous, ochraceous, deeper on the fifth segment. 



Cephalothorax a little wider than long, about as long as the 1st 

 caudal segment and ^ the 2nd ; not carinate, coarsely and evenly 

 granular almost throughout, the granules finest in the middle of the 



* This specimen shows signs of having lost its colour. Fresh examples would 

 probably be much more brightly tinted. 



