286 Proceedings of the Royal Physical Society. 



decidedly more numerous the closer we get to the Antarctic 

 continent. In America, for example, there are four species 

 found in S. Georgia, the Falklands, and Patagonia, two in 

 Chili, and one in N'orth America. I have mentioned a few 

 instances here ; but Mr Blanford has lately argued with 

 considerable force in favour of an ancient land connection 

 between these countries by the extension of the Antarctic 

 continent. Quoting many instances of closely-allied forms 

 of life, and especially laying stress upon the facts that 

 America and New Zealand are not separated by a depth 

 greater than 2000 fathoms from the southern land mass, he 

 also points out that there are not any soundings due south of 

 Cape of Good Hope ; hence it is possible that the ocean here 

 may be no deeper. 



On the other side, we have seven species in New Zealand 

 as against one in Australia. 



The African continent does not, it is true, furnish much 

 evidence for this position as far as decrease of species as w^e 

 pass northwards is concerned; but, on the other hand, the 

 absence (?) of the genus from North Africa, and at any rate 

 its certain absence from Europe, shows that either the Desert 

 of Sahara or the Mediterranean has formed a bar sufficient 

 to prevent the immigration of this genus from the south 

 northwards. 



There is an unmistakable aojreement also between the 

 Old and New World tropics. The following generic types 

 are common to the two : — Perichmta, Urochceta, and Bhino- 

 drilus. On the other hand, the genera Diachmta, Onychochmta, 

 Urobenus, Trigaster, Geoscolex, and Anteus are peculiar to the 

 New World ; while Typhceus, Perionyx, and Moniligaster are 

 peculiar to the Old. 



There is not a marked agreement in species. Urochaita 

 corethrura, Periclweta indica, P. affinis, and P. Hoidleti are 

 the only forms which are common to the Neotropical and 

 Oriental reojions. 



This resemblance is probably largely due to climatal 

 causes. Pericha^ta, although an almost world-wide genus, is 

 decidedly more abundant as we approach the hotter regions. 



