278 STUDIES, SCIENTIFIC AND SOCIAL chap. 



Europe and America at about the latitude of London, 

 without implying a greater amount of subsidence than 

 would balance the elevation which we know has occurred 

 over extensive areas in Europe and America. We also 

 know that two of the most characteristic tropicopolitan 

 forms — the tapirs and the trogons — existed in Europe in 

 Miocene times ; and every geologist will admit that there 

 must have been many others, especially among birds and 

 reptiles, whose remains we have not yet discovered, and 

 never may discover. The transmission of similar forms to 

 tropical Africa and Asia has already been explained in 

 reference to Pitta angolensis ; and thus, it appears to me, 

 the problem of tropicopolitan forms is completely solved 

 without making any assumptions but such as are 

 warranted by admitted geological and palseontological 

 facts. It has been necessary to treat the question 

 oroadly ,and to omit many details which require fuller 

 elucidation. I can only now call attention to the obvious 

 fact that the geological age of the remains of any animal 

 type in a given area cannot be held to denote the period 

 of its earliest appearance in that area by migration or 

 otherwise, because, till it became somewhat abundant, 

 there would be little chance of its remains being preserved 

 or discovered. This will apply to the case of the tapirs, 

 which are supposed to have migrated to North America 

 in the Miocene period, but whose fossil remains are not 

 found in any deposits earlier than the Pliocene. 



Relations between the West Indies and Madagascar. 



We will now return to Dr. Sclater's fourth problem, that 

 of the occurrence of the curious insectivorous mammal, 

 Solenodon, in the Antilles, while its nearest allies are to be 

 found in Madagascar. By the help of the conclusions we 

 have already arrived at, much of the marvel and difficulty 

 of this curious case of geographical distribution vanishes. 

 It is simply an extreme instance of a family of animals 

 which has been long dying out, but which maintains a 

 lingering existence in two remote island groups where it is 

 comparatively free from the competition of higher types, 



