382 ORIGIN OF LIFE IN AMERICA 



finally destroyed until early Tertiary times (compare Figs. 15 

 and 20). Quite recently, however, Dr. Ortmann * argued that 

 this " Archhelenis " of Dr. von Ihering must have sunk 

 beneath the waves of the ocean by the end of the Mesozoic E'ra. 



Some time ago Mr. Pocock f pointed out that the scorpions 

 of the genus Opisthacanthus were confined to tropical Africa, 

 Madagascar and South America. Our knowledge of the dis- 

 tribution of scorpions has increased considerably since he 

 wrote his essay, but the range of Opisthacanthus has not been 

 greatly extended. It occurs in west, east and south Africa 

 and Madagascar, while it reappears on the opposite side of the 

 Atlantic in Colombia and the island of Haiti. It is not known 

 from either Brazil or Guiana and may possibly have become 

 extinct there. On the other hand, Damon, one of the Tarantu- 

 lidae, occurs in west and east Africa and from Brazil to Pata- 

 gonia. Professor Kraepelin J assumes that because the African 

 Damon variegatus in a specifically identical form actually 

 inhabits South America, it must have been introduced into the 

 latter continent, yet in another place he urges that several 

 of the centipedes (Scolopendridae) probably maintained their 

 specific characters from archaic times to the present day. Like 

 some of the species of Otocryptops, Rhysida and Scolopendra 

 and the curious arachnid Cryptostemma, Damon variegatus 

 may possibly represent one of these ancient species which 

 has retained its morphological characters unchanged since 

 Mesozoic times. 



The numerous examples, cited above, indicate that there 

 exists a perfectly recognisable faunistic relationship between 

 tropical Africa and tropical South America. Nevertheless this 

 relationship rarely extends to genera and species. If so it is 

 confined to forms like Anops, 'Mabuia, Subulina, Opistha- 

 canthus, Cryptostemma and others, of which there is reason 

 to believe that they are extremely ancient types. From some 

 cause or other they may have retained their specific or generic 

 characters throughout a series of geological ages. The faunas 

 of Africa and South America as a whole are thoroughly dis- 



* Ortmann, A. E., " Tertiary Archhelenis," p. 242. 

 t Pocock, E. I., " Distribution of Arachnida," p. 229. 

 J Kraepelin, K., " Scorpiones and Pedipalpi," p. 240. 



