ON THE PEDirALPI OF NORTH AMERICA. 359 



Fam. I. SCORPIONID^. 



Dens mandibularis horizonti in libella movens. Pedum par anticum haud elongatum, sed alteris simile. 

 Abdominis appendix caudalis et crassis et longa. 



The natural arrangement of this family is still enveloped in obscurity. De Geer 

 in his Memoires pour L' Hist, des Insectes vol. vii. p. 337, divides them into " Des 

 ' Scorpions de la premiere familie ou de ceux a six yeux" and "Des Scorpions de la 

 seconde familie, ou de ceux a huit yeux." Linnosus recognized but one genus. 

 Dr. Leach, in 1815, (Linn. Trans, vol. xi. p. 391,) founded a second, depending on 

 the ocelli for his characters. Since then the list has been swelled by several authors, 

 mostly, by the extension and development of these characters. In Apteres, vol. iii. 1844, 

 (Suites a BufFon), M. Gervais acknowledged but one genus and various sub-genera. 

 While Koch. (Arachnid. Syst.) in 1850, elevated the Scorpionidge to the rank of an 

 order, designating many of the suh-genera of Gervais, (genera of other authors,) as 

 families, and indicating numerous new genera. 



In 1861, Prof. Peters, (Monatsberichte, p. 508,) published an entirely new classi- 

 fication, basing it on hitherto unused characters. Whatever emanates from such 

 authority, should be received with great deference. With our present supply of 

 foreign specimens, we do not feel entitled to condemn it absolutely. But if we adopt 

 it, we would necessarily propose several new sub-families and genera. This we cer- 

 tainly are not prepared to do, and have in this paper retained the number of ocelli 

 as the genuine criterion. 



o^ 



S. ALLENII. 



Synopsis of (he Scarpionidcs of North Amerieit. 



Gen. I. SCORPIUS, Oculi 6. 



Gen. II. BUTHUS, Oculi 8. 



* Lateral eyes arranged in a straight series. Tail armed loith a basal spine to the sting. 

 B. BiACULiATUS. — Color cinnamon and nearly uniform. Abdomen very strongly 



granulate and tuberculate. Length 3 J inches. 



B. CAROLiNiANUS. — Color fulvous, striped very dark brown. Cephalothorax macu- 

 late. Abdomen but moderately granulate and tuberculate. Length 2? iuches. 



B. CALiFORNicus. — Color nearly the same as in the last ; cephalothorax immaculate. 

 Abdomen strongly granulate. Length 2 inches. 



* * Lateral eyes arranged in a slightly curved series. Tail toith a basil spine to sting. 

 B. LESEUEEii. — Hands very much swollen* 



* * * Eyes in a straight or nearly straight series. Sting loithout the basal spine. 



B. EXILICAUDA. 



