GRENADA. 235 



In 1910 when I published my Notes on the herpetology of Jamaica, I quoted 

 Dr. R. T. Hill as believing that the West Indies "have persisted without Conti- 

 nental connection or union with each other since their origin." He wrote this 

 after the publication of his Notes on the geology of the island of Cuba (Bull. 

 M. C. Z., 1895, 16). I find however by re-studying his Geology of Jamaica 

 that after his more prolonged examination of the geology of Jamaica he changed 

 his opinion very radically, for here (Bull. M. C. Z., 1899, 34, p. 224) he says: — 



" In late Oligocene or Miocene time there was a tremendous orogenic movement which 

 resulted in uplift, whereby many of the islands were connected with each other, and possibly 

 an insular southern portion of Florida, but not establishing land connection with the North 



and South American continents In Miocene or early Pliocene time the islands were 



severed by submergence into their present outlines and membership, which they have since 

 retained with only secondary modification." 



It will be seen that these views agree more closely with the conclusions 

 which are forced by an interpretation of the facts presented by the distribution 

 of existing animals. The Lesser Antilles have probably been subject to more 

 violent disturbances than the Greater. Nevertheless the existing species show 

 that nearly all of the islands if not every one of them, has never been completely 

 submerged since their original breaking away from the land which now forms 

 northeastern South America, or more probably that part of it which is repre- 

 sented in remnants by the great flat-topped mountains such as Roraima in 

 British Guiana. Grenada and possibly some of the other more southerly Lesser 

 Antilles have probably been in temporary union with the mainland once or 

 twice since the first connection was severed. 



Regarding the origin and affinity of the Grenadian fauna, then, we may 

 summarize by saying that in its salient features it is a typical Antillean island 

 fauna. It shows closer affinity with South America than the other islands to 

 the northward. It has evidently been connected with South America after it 

 became separated from St. Vincent and the other islands north of it; and this 

 separation may have been caused by subsidence, accompanied by a slow folding 

 which began north and progressed to the southward, separating the islands suc- 

 cessively from one another. This is suggested by the progressive diminution of 

 typical South American forms from south to north. The geological structure 

 of many of the islands of the inner Antillean arc is so masked by the products 

 of extensive and recent volcanic activity that the zoologist can look for but little 

 assistance from the geological investigation of these islands. Their past history 

 will only be definitely known when the land fauna of each island is completely 

 investigated. 



