46 



area with a median elongate yellow 



patch ; hand in tf thick 7. thurstoni, p. 47. 



V. Pectinal teeth 17-19 ; ante-ocular 

 area with a large triangular yellow 

 patch ; hand in J thin 7. eurojieeua, p. 46. 



32. Isometrus europaeus, Linn.Syst. Nat. ed. 10, p. 625,1758 (Scorpio) ; 

 Lonnberg, A.M.N.H. (7) i, p. 86, 1897 (Isometrus): maculalus, 

 De Geer, Mem. Hist. Ins. vii, p. 346, pi. xli, tigs. 9 & 10, 1778 

 (Scorpio); C. L. Koch, Arachn. xii, p. 1, fig. 960, 1845 (Lychas); 

 Thorell, A. M. N. H. (4) xvii, p. 8, 1876 ; Simon, Ann. Mtu' Genov. 

 xx, p. 370, 1884 ; Oates, Jour. Bom. N. H. Soc. iii, p. 250, figs. 3, 4, 

 1888 ; Kraep. Jb. Hamb. wiss. Anst. viii, p. 245, 1891 (Isometrus) : 

 dentatus & americanus, Herbst, Nat. Unyefliigdt. Ins. iv, pp. 55 

 & 60, pi. vi, tigs. 2, 3, 1800 (Scorpio) : filum, Hempr. $ Ehrenb. 

 Symb. Phys., Scorp. p. 3, t. i, fig. 3, 1828 (Buthus (Isometrus)). 



Colour yellow varied with black; carapace marked in front 

 with an anteriorly-expanding triangular yellow patch reaching the 

 anterior border. Terga ornamented along the posterior border 

 with five black spots, separated by six spots of a clear yellow tint. 

 Sterna yellow, the last obsoletely lined with black. On the tail 

 the black on the upper side is represented mostly by small spots 

 along the keels ; on the under side, the black forms a network ; 

 hand externally spotted : fingers brown, black at base, yellow at 

 tips. 



$ . Carapace evenly granular throughout ; about as long as the 

 1st and half the 2nd caudal segments or as the 4th. Terga evenly 

 granular. Sterna smooth, the last 

 granular throughout, with four 

 granular crests. Tail slender, 

 about five and a half times the 

 length of the carapace, evenly 

 granular; 1st segment longer than 

 wide, 4th about three times as 

 long as wide ; median lateral keel 

 practically absent on the 2nd : 

 vesicle (fig. 12, A) granular below ; 

 the spine triangular-pointed, fur- 

 nished with a single anterior 

 denticle, separated at its origin 

 from the aculeus by a space equal 

 to the thickness of its own base or 

 of that of the aculeus. Chelae 

 finely granular and granularly 

 crested; brachium with an upper 

 and a median crest on its posterior 

 side; hand smooth, keelless, scarcely 

 as wide as brachium; underhand 

 less than half the length of the movable finger, which is longer 

 than the carapace. Pectinal teeth 17-19 ( tf , $ ). 



A. 



C. 



Pig. 12. A. Isometrus europeeus: 



vesicle and aculeus. 

 B. Ditto : extremity of chela of 



male. 

 C. Isometrus thurstoni : extremity 



of chela. 



