Prof. T. Tliorell on the 



2. Lateral teeth of the palp-fingers form, both ou the inuer and outer 

 side, a row of teeth placed two and two transversely near to 

 each other. (The tooth under the sting is sometimes wanting.) 



TiTYUs, (C. L. Koch), 1836. 

 Type T. lincafus, C. L. Koch, 1845, 



Inferior margin of the immoA-able mandibular finger armed with one 

 (very small) tooth. (A tooth or spine mider the sting is rarely 

 wanting.) 



* Both the inner and the outer latera,l teeth of the palp-finger8 

 arranged in a single row. 



1. Thelifthcaudal joint broadly excavated above, its upper margins 



forming an elevated keel. (The tail gradually somewhat in- 

 crassated from the vicinity of the base to the fifth joint.) 



Phassus, n.^ 

 Type P. colmnbianus, n.^ 



2. Upper margins of the fifth caudal joint rounded, not forming 



an elevated keel Isometrus, (Il^nipr. et h]hr.), 1829. 



Type /. macidatus, (DeGeer), 1778''. 



plus minus infuscata; segmentis abdominalibus costis trinis versus 

 medium, postice, munitis ; cauda gracili, segmentis l°-4™ subcylindratis 

 et carinis inferioribus mediis carentibus, carinis reliquis debilissiniis, 

 subtiliter deuticulatis ; segmento 5° carinis superioribus carente, saltern 

 duplo et diniidio longiore quani latiore ; vesica sub aculeo mutica ; 

 digito manus mobili manu postica non vel vix longiore, ordinibus 

 deutium secundum mediam aciem ejus 9; deutibus pectinum 29-31. 

 Long, circa 47 niillim. Africa, Cafiraria. 



^ Nom. propr. mythol. 



^ Phassus colunihianus, n. 



Cephalothorace sat ci-asse granuloso, nigro et fusco-testaceo variato, 

 abdomine nigricante, ordinibus 5 longitudiualibus macularum fusco- 

 testacearum ; cauda basi fuso-testacea, apice late nigricante, ibique sat 

 fortiter angustata, vesica parva, oblonga, crasse granulosa, sub aculeo 

 dente forti compresso supra bidenticulato armata ; manibus brachia 

 latitudine fere sequantibus, evidentissime granuloso-costatis ; digito 

 manus mobili manu postica duplo longiore, ordinibus denticulorum 

 secundum mediam aciem ejus circa 8; dentibus pectinum fere 12. 

 Long, circa 32 millim. America merid., Columbia. 



3 = Scorpio atnericKs, Linn., 1758. I suppose we cannot well retain the 

 Linnean name of this scorpion, as Linnaeus had already in 1754 (in hia 

 ' Museum Adolphi Friderici,' where the binominal nomenclature is con- 

 sistently and constantly employed) given the name »S'. amcricanus to another 

 species of Isometnis. In his ' Syst. Nat.' ed. 10 (1758) and in ' Mus. 

 Ludov. Ubicse ' (1764), Linnaeus changed the name of that scorpion, er- 

 roneously considering it identical with a European species, into aS'. em-opceus, 

 although tlie specimen which he had described was from Avwrica. This 

 S. americamis, Linn. 1754, or S. europceus, ejusd. 1758, in which, according 

 to Linnaeus (Mus. Ludov. Tlricae, p. 429), the hands are " supra augulatae, 

 admodmn anr/usta,'" is no doubt identical with »S'. eiiropceus, DeGeer (of 

 which I have seen the type specimen), or <S'. ohs('arus, Gerv., which species 

 I therefore call Isometnis amcricatms, (Linn.). 



