BARBOUR : NOTES ON THE HERPETOLOGY OF JAMAICA. 277 



gence from the characteristic Greater Antillean fauna is the absence of 

 Bufo and Aniphisbaena. On the other hand, the island shares with 

 San Domingo the peculiar genus Aristelliger. The autogenus Xipho- 

 cercus is generically separable from Auolis, from which it has been 

 derived. 



A peculiarity of the fauna of Jamaica is the fact that while its prox- 

 imity to Cuba is practically the same as its distance from Haiti, the evi- 

 dent relationship of the island's fauna with that of Haiti is well marked, 

 while with Cuba it has in common only species which range widely 

 through the West Indian region. Now a possible explanation of this 

 offers itself when we examine a contour map of the Caribbean Sea. One 

 of these was published as Fig. 57 in Mr. Alexander Agassiz's "Three 

 Cruises of the Blake" (Bulletin of the Museum of Comparative Zoology, 

 1888, 14). :Mr. Agassiz showed here that the Bartlett Deep, of over 3000 

 fathoms, extends between Cuba and Jamaica — doubtless a cleft of very 

 ancient origin. The depth of water, however, between the great southern 

 arm of Haiti and Jamaica is only from -500 to 800 fathoms. There is, it 

 is true, a hole of a depth greater than this south of the Formigas Bank. 

 This, however, is very limited in area, and does not fundamentally affect 

 the condition of affairs. The water between Jamaica and the Mosquito 

 Coast of Centi'al America is, much of it, extremely shallow, mostly 100 

 fathoms or less ; though between the Pedro Bank and the Eosalind Bank 

 there is a narrow stretch of water of about 500 fathoms depth. 



Hydrographically, then, Jamaica is intimately related with both Cen- 

 tral America and Haiti, and it seems probable that Lesser Antillean spe- 

 cies and Central American species have come through a land connection 

 which had nothing to do with Cuba. This would account, for instance, 

 for the presence of Aristelliger in Haiti and Jamaica. The early separa- 

 tion of Jamaica from the mainland and from Haiti would account for the 

 absence of types having such a distribution as Bufo and Amphisbaena ; 

 which may easily liave reached Haiti from the mainland of Central Amer- 

 ica by way of Cuba. For another connection must have existed between 

 Cuba and the upper peninsula of Haiti after the separation of Jamaica 

 from Haiti, and may we not suppose that the separation took place be- 

 fore the migration of Bufo or Amphisbaena had extended far enough 

 to have reached Jamaica before it was separated ] 



That the question is far more complex than the suggestions contained 

 in the previous paragraphs would indicate is undoubted. Wallace, in his 

 " Geographical Distribution of Animals " (London, 1876, 2, p. 81), says : 

 "The West Indian Islands have been Ions: isolated and have varied much 



