362 ON THE rEDirALPI OF NORTH AMERICA. 



Androctonus biaculeatus, Lucas. Hist, des Canaires par Webb et Bartbelot Arach. p. 45 (according to 

 Gervais.) 



Scorpio (Atreus) biaculeatus, Gervais, Apteres, vol. iii. p. 54. vol. iv. pi. 23, f. 3. Exp. de 1' Amerique du 

 Sud. par M. Castelncau. Sept. part. (Blyriap. et Scorp.) p. 43, pi. ii. fig. 4. 



Scorpio (Atrcus) Edwardsii, Gervais, Arcbiv. Mus. vol. iv. p. 216, pi. xi. fig 13—15. Apteres, vol. iii. 

 p. 53. Exp. dans l'Ameriq. du Sud. part. Sept. (Myriap. et Scorp.) p. 41, pi. i. fig. 1. 



Scorpio (Atreus) De Geerii, Gervais, Arcbiv. Blus. vol. iv. p. 217, pi. xi. fig. 16-17. Apteres, vol. iii. 

 p. 54. Exp. dans l'Ameriq. de Sud. part. Sept. (Myriap. et Scorp.) p. 



Scorpio (Atreus) ohscurus, Gervais, Arcbiv. Mus. vol. iv. p. 219, pi. xii. fig. 26. Apteres, vol. iii. p. 55. 



The cephalothorax is shallowly emarginate in front. The median furrow is very 

 deep in its posterior portion. The anterior margin is very rough and tuberculate. 

 The median eyes are placed near to the junction of the anterior and middle third, 

 and are surmounted by a strongly marked curved crest or brow. This extending 

 some distance in front, becomes crenulate. The surface is very much roughened, by 

 tubercles disposed in rows. The maxillary palpi are rather slender, with their mar- 

 gins strongly crenulate, or more rarely denticulate ; on their anterior face are nu- 

 merous spinous tubercles. The third joint has on its upper surface a very distinct, 

 crenate ridge. But as is the case with the margins of this articulation also, the cre- 

 nations are often feeble. The hand is irregularly sub-parallelopipedal with its an- 

 terior face very convex. Its postero-inferior, superior and antero-superior margins are 

 provided with well-marked but not crenulate raised lines. The fingers are very long, 

 but at the same time rather robust. Their opposing margins are armed with a series 

 of central, obliquely longitudinal, imbricated rows of small teeth. On either side of 

 these, larger ones are arranged similarly but irregularly. The abdominal scuta have 

 their anterior surfaces minutely granulate. Their posterior roughened by numerous 

 tubercles, which are arranged in curved series, presenting their concavities forward. 

 The mesial keel is often crenulate. The posterior margins are provided with sub- 

 spinous tubercles. The last true abdominal scutum presents superiorly a pair of 

 strongly pronounced, nearly straight crenulate ridges. These, although convergent 

 posteriorly, are generally not connected by any cross lines. In some specimens, how- 

 ever, reaching to the posterior margin, they are thus joined together. But near their 

 proximal end a transverse row of crenations connects them with a more external 

 ridge similar with and nearly parallel to themselves. The tail in the male is long and 

 slender. In the female, both shorter and more robust. The median lateral crests 

 exist only on the first joint. The four anterior joints have the superior, supero-lateral, 

 the infero-lateral, and the inferior crests well developed. The inferior ridges of the 

 fourth segment are often not crenulate. The penultimate articulation in the male is 

 very often subcylindrical and without a crest. We have examined the young of this 

 species from those a few lines in length to the adult. They are first of a dark purple 

 color with a light median stripe. But they soon acquire the peculiar specific charac- 



