On tlie Flora and Fauna of Santa Ortiz. 11' 



VII. — On the Relations of the Flora and Fauna of Santa Cruz, 



West Indies. 



BY THOMAS BLAXD. 



Read January 3,1, 1881. 



Professor A. Agassiz (Ball. j\las. Comp. Zool. , Cambrido^e, V, 

 Nos. 14, 289, June, 18T9) remarks, "One of the most interest- 

 ing results reached by this year's cruise, is the light thrown upon 

 the former extension of the South American Continent, by the 

 soundings taken while dredging, and those subsequently made 

 in the passages between the islands by Commander Bartlett. 

 These, together with the soundings already known, enable us to 

 trace the outline of the old continent with tolerable accuracy, 

 and thus obtain some intelligible, and at the same time trust- 

 worthy, explanation of the peculiar geographical distribution of 

 the fauna and flora of the West India Islands." 



Professor Agassiz writes (L c. ) : "In attempting to recon- 

 struct, from the soundings, the state of things existing in a 

 former period, we are at once struck by the fact, that the Virgin 

 Islands are the outcroppiugs of an extensi\e bank. The great- 

 est depth between these islands is less than forty fathoms, this 

 same depth being found on the bank to the east of Porto Rico, 

 the 100-fathom line forming, in fact, the outline of a large 

 island, which would include the whole of the Virgin Islands, 

 the whole of Porto Rico, and extend some way into the Mona 

 Passage." * * "On examining the 500-fathom line, we thus 

 find that Jamaica is only the northern spit of a gigantic pro- 

 montory, which once extended toward Hayti from the mainland, 

 reaching from Costa Rica to the northern part of the Mosquito 

 coast, and leaving bnt a comparatively narrow passage betAveen 

 it and the 500-fathom line encircling Hayti, Porto Rico, and 

 the Virgin Islands, in one gigantic island. The passage between 

 Cuba and Jamaica has a depth of 3,000 fathoms, and that be- 

 tween Hayti and Cuba is not less than 873 fathoms, the latter 

 being probably an arm of the Atlantic. The 500-fatliom line 



