130 Mr. E. I. Pocock on the 



nected with the genital operculum set forth in the above 

 synopsis. 



Loc. Central America and Brazil. 



The type of the genus has the following synonymy : — 



Mastigoproctus giganteus (Lucas). 



Thelyphonus giganteus, Lucas, Mag. Zool. pt. viii. (1835) ; Koch, 



Arachn. x. p. 21, figs. 767, 768. 

 Thelyphonus excubitor, Girard, Expl. of Red River, p. 265, fig. xvii. 

 Thelr/phonus ? mexicanus, Butler, Ann. & Mag. Nat. Hist., Sept. 1872, 



p. 201. 

 Thelyphonus rufus, id. ibid. p. 205. 



The British Museum has a large number of examples of 

 this species from various parts of Mexico and a few from 

 Texas. 



I believe that the form named mexicanus by Butler is 

 merely the male not quite adult; but I have not seen quite 

 enough examples of this sex to be able to establish the truth 

 of my belief. 



I also refer to this genus the species described by Tarnani 

 as Thelyphonus maximus, of which the Museum has a single 

 male example from Matto Grosso, in Brazil. I suspect, how- 

 ever, that this so-called species is the male of Th. brasilianus 

 of Koch, and I do not feel satisfied that Th. brasilianus of 

 Tarnani is identical with the species so-named by the German 

 arachnologist. 



I provisionally refer to this genus Th. proscorpio of 

 Latreille * ( = antillanus of Koch and caudatusoi Tarnani), of 

 which the Museum has a considerable number of females 

 from Haiti. But my ignorance of the male characters makes 

 the reference doubtful. The same remarks apply to the 

 species described below as M. Butleri. 



Mastigoproctus Butleri, sp. n. (PL II. tigs. 5, 5 a.) 



Thelyphonus brasilianus, Butler, Ann. & Mag. Nat. Hist., Sept. 1872, 

 p. 201. 



Colour blackish red above, paler below. 



Carapace thickly and rather coarsely granular throughout, 

 the ocular keel complete and finely serrate, the area below it 

 vertical, the anterior extremity of the carapace also almost 



* Latreille expressly stated that the species he named proscorpio was 

 an inhabitant of the West Indies. 1 consequently adopt this specific 

 name for the form that Koch subsequently described as antiUatius ; but 

 I cannot see that Tarnani has any grounds for calling this species caudatus 

 of Linn., the latter being, as Stoliczka and Thorell have pointed out, a 

 Javan form. 



