82 Mr. R. J. Pocock on Neotropical Scorpions. 
prominent. The ocular tubercle prolonged in front almost as 
far as the anterior emargination ; the anteocular area there- 
fore is not mesially grooved. 
This genus resembles Chactas, except that in Ohactas the 
ocular tubercle is short and terminates in front in a point 
from which a deep groove runs forwards to the (usually) 
shallow emargination of the anterior border; the anterior 
lateral eyes too are generally very prominent. It also very 
closely resembles Teuthraustes, of which the British Museum 
has several examples, referred to atramentarius, from Ecuador ; 
but in this last genus the anteocular region of the carapace 
is much more strongly sloped downwards and forwards and 
the anterior border is not or scarcely emarginate. 
Heterochactas Gervaisiz, sp. n. 
Colour piceous, with ferruginous legs and vesicle and 
redder feet. 
Carapace nearly as long as the first three caudal segments, 
nearly smooth above, somewhat thickly granular at the sides, 
the median sulcus not continued in front of the ocular tubercle ; 
the anterior border somewhat deeply emarginate in the middle, 
rounded at the sides ; the anterior lateral eye not prominent ; 
median eyes small, separated by a distance about equal to 
three diameters. 
Tergites nearly smooth, at most obsoletely granular, the 
last finely and closely granular, with two tubercles on each 
side. 
Sternites smooth and polished. 
Tail about three and a half times as long as the carapace ; 
the anterior four segments smooth beneath and not keeled, 
marked with a few coarse punctures; the upper surface 
scarcely excavated and very feebly granular, the fourth and 
fifth segments entirely flat, the superior and supero-lateral 
keels present and finely granular, as also are the spaces between 
them ; the tail narrowed posteriorly, the second segment a 
little wider than long, the third a little longer than wide, the 
fifth more than twice as wide as long, finely granular above, 
flat in its posterior two thirds, its edges squared and granular, 
its sides and lower surface also finely granular, with a poste- 
riorly abbreviated weak median lateral keel and granular 
anteriorly weak inferior keels; vestcle large, higher and con- 
siderably wider than the fifth segment, granular below and at 
the sides, flat and suleate above; vesicle short. 
FPalpti robust, not large; humerus granular above and in 
front and carinate ; brachium not denticulate nor granular, 
