1890. J OF THE FAMILY BUTHID.E. 119 



is, in my opinion, very much to be deprecated, I have added Tityus 

 to the synonyms o( Isometrus, and have taken Peters's name Uroplectes 

 for the species which Thorell called TiUjiis. This, however, J. have 

 done on the authority of Dr. Karsch, who in a footnote to his table 

 of o-enera says that Uroplectes is synonymous with Tityus in Dr. 

 Thorell's sense of the word. Presumably this statement is made 

 after an examination of the tyj)e of Uroplectes, namely U. ornatus. 

 If this, however, be not so, it will be well to bear in mind that there 

 is nothino- in Peters's diagnosis of ornatus to show that the species is 

 not referable to Lepreus. In tliat case Lepreus will have to rank as 

 a synonym of Uroplectes, and a new generic name will have to be 

 established (or tlie species here included under Uroplectes, unless the 

 alternative be adopted of considering all the species of Lepreus and 

 Uroplectes as referable to one genus Uroplectes'. 



Genus Isometrus, Ehrb. 



Isometrus, Ehrenberg, Symb. Phys. (Scor[)iones), p. .>, pi. i. fig. 3 

 (ISO'J) — type _/ilH7n = niaculatvs (Dc Geer). 



Tityus, C. Koch, Die .\rach. lii. p. 33( 1^36)— type ba7iiensis{PeTty). 



Pilumnus, id. Arach. Syst. p. 38 (1837) (nom. prceocc). 



Lychas,\d. Die Arach.xii. p. 1 {]^-\f))—iy\)e maculatiis (De Geer). 



Atreus,i3tex\. Apt. iii. p. 52 (1844) (in part), not of C. Koch, 1837, 



Centrurus, Peters, Monatsb. Ak. Wiss. Berlin, 1862, p. 512 (in 

 part) . 



Isometrus, Thorell, Etudes Scorpiol. p. 9 (1S7C) (and subsequent 

 authors). 



Phassus, id. ibid. 



Androcottus, Karsch, Mitth. Miinch. ent. Ver. p. 1 1 (18/9). 



Hab. Tropical countries. 



Inferior border of the immovable digit of the chelicerse armed 

 with a single tooth. 



The external series of teeth on the digits of the chelse formed by 

 the assumption of a more or less transverse position of the posterior 

 one or two enlarged teeth of the median rows ; the internal 

 series of teeth formed by the enlargement and separation of the 

 anterior tooth of each of the median rows ; but this separation is 

 never carried to any great extent. In most of the Old- World species 

 the median rows scarcely overlap each other ; but in the larger 

 American forms, such as I. androcotloides, the rows overlap to 

 such a degree that the anterior extremity of any one reaches the 

 middle of the row in front of it. 



The cephalothorax is usually without well-developed keels ; the 

 tergites are nearly always provided only with a median keel ; the 

 tail is, as a rule, keeled above and below, and the vesicle is nearly 

 always provided with a strong spine beneath the aculeus. 



The sexes generally differ considerably and in a variety of ways : 

 thus the male of/, messor and of 7. maculatus has long chelse with 

 slender hands and a long tail ; I. tricarinatus has short chelse with 

 thick hands and a long tail ; /. mucronatus (varius) has a thick hand 



1 I have refrained from definitely uniting the two genera, because pilosus 

 the type of Lepreus, is unknown to me. 



