FORMER LAND CONNECTIONS. 825 



Pseudohymenochirus, in Africa, and Pipa in ooutli America) : 

 also, that of the Caponiid and Sicariid spiders. 



But in other instances mentioned by Mr. Pococlx, the 

 evidence, though admittedly incomplete in the total absence of 

 palaeontological data, seems to me more favourable to an Afro- 

 American land connection. 



(Ij The Ischnurine scorpions are lo-day widely distributed, 

 being known from the Ethiopian region, Madagascar, Oriental 

 region from India to Papua, and from the noruiern part of the 

 Neotropical region. There are four genera in Africa, one of them 

 Opisthacanthus (about 10 species) occurring also in Madagascar 

 (1 species) and in Central America (1 or 2 species). Another 

 genus, Hadogenes, is confined to Southern Africa and Mada- 

 gascar, whilst lomachus occurs in Southern India and East 

 Africa. Another genus, Hormurus, is Indian, Malayan and 

 Australian, and there is a peculiar genus confined to Zanzibar, 

 the Seychelles and Round Isle. Opisthacanthus is abundant and 

 widespread in the Ethiopian region, extending through bush and 

 forest districts from the neighbourhood of Capetown along the 

 southern coast and far into the tropics of West Africa. 



Thus the Ischnurine scorpions of Central America and of 

 West Africa have a particularly close affinity, definitely greater 

 than that between the W^est African and Malayan genera or 

 between those of Asia and America. There is, moreover, nothing 

 to show that Opisthacanthus represents the ancestral stock of the 

 Ischnurine scorpions. The genus is certainly more generalised 

 than either Cheloctomis or Hadogenes, the other South African 

 members of this group, but not more so than the Oriental 

 Hormurus. Critics may assume that Opisthacanthus has migrated 

 through Eurasia and North America, when the climate of northern 

 lands was milder than iv is to-day, but the argument would be 

 more convincing if the genus had a wider distribution in the 

 Old World tropics, especially in view of its adaptability to widely 

 different climates in Africa. 



(2) The Onychophora is the group of terrestrial invertebrates 

 commonly called Peripatus. There are two families, the Peri- 

 patidae and Peripatopsidae. A. H. Clark^ divides the Peripatidae 

 into two sub-families: — (a) The Eoperipatinae with two genera 

 confined to the Malayan region and Tibet; and (b) the Peripatinae 

 with three genera, one in French Congo (Mesoperipatus) and the 

 other two in tropical America (Peripatus and Oroperipatus). The 

 most primitive genus is Oroperipatus of South and Central 

 America west of the crest of the Andes ; and then follow in 

 increasing order of specialisation, Peripatus of Eastern South 

 and Central America, Mesoperipatus of French Congo, and finally 

 the Eoperipatinae. 



The other family Peripatopsidae also has two sub-families: — 

 (a) The Peripatoidinae with three genera, one in Australia, New 

 Zealand and Tasmania, one in Chili and Aconcagua, and one in 

 South Africa (Opisthopatus), the latter being much more closely 

 related to the American genus than to the Australian; and _(b) 

 the PeripatoDsinae with one South African genus (Peripatopsis), 

 and one in New Britain, New Guinea and Ceram. 



