BIOLOGIA CENTRALI-AMERICANA 



Z00L0GIA. 



Class ARACHNIDA. 



Order SCORPIONES. 



Key to the Families of Central- American Scorpions. 



a. Legs furnished with a single pedal spur on the anterior side of the 



arthrodial membrane connecting the tarsus and protarsus. Sternum 



pentagonal ; the two halves of the genital operculum united in the 



female . . . <. Scorpionid^. 



a 1 . No subaculear tooth on caudal vesicle Subfam. IscHNURiNiE. 



b 1 . A distinct subaculear tooth on the caudal vesicle ...... Subfam. Diplocentrin^e 



b. Legs with a pair of pedal spurs between the tarsus and protarsus ; 



the two halves of the genital operculum separated in both sexes. 



a 2 . Sternum with parallel or subparallel sides, pentagonal; the pedal 



spurs simple, unbranched ; immovable linger of mandible with- 

 out an inferior tooth Ymjovid/e. 



b 2 . Sternum triangular, with anteriorly converging sides ; anterior 



pedal spur bifid ; immovable finger of mandible with one inferior 



- 



tOOth BUTHIM;. 



Earn. SCORPIONID^. 



Subfam. I8CHNURIN^J. 



OPISTHACANTHUS. 



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Opisthacanthus, Peters, MB. Ak. Wiss. Berlin, 1861, p. 511 ; Thorell, Ann. & Mag. Nat. Hist. (4) 



xvii. p. 11 (1876) ; Pocock, Journ. Linn. Soc, Zool. xxiv. p. 397 (1893) ; Ann. & Mag. Nat. 

 Hist. (6) xvii. p. 312 (1896) ; Kraepelin, Jahrb. Hamb. Wiss. Anst. xi. p. 118 (1894) (part.) ; 

 Das Tierr., Scorpiones et Pedipalpi, p. 146 (1899). • , 



Opisthocentrus , Pocock, Ann. & Mag. Nat. Hist. (6) xii. p. 316 (1893). 



Carapace deeply excised anteriorly, longitudinally sulcate throughout ; ocular tubercle subcentral ; three 

 lateral eyes on each side. Tail thin, compressed, rather short. Chelce robust, the brachium armed at 

 the base in front with a large tooth-like prominence ; upperside of the hand divided by a strong crest 

 into two areas, the external of which is nearly vertical and meets the internal horizontal area at an obtuse 

 or a right angle, the vertical area separated by a strong keel from the underhand, which is completely 



biol. centk.-amer., Arachn. Scorp., May 1902. 



