334 ANNUAL OF SCIENTIFIC DISCOVERY. 



days ; and he represented the natives as physically a most miserable 

 race. Mr. Schoolcraft said, that it was then a popular error that they 

 were of taller stature than other Indians. National Intelligencer. 



DISTRIBUTION OF THE TESTACEOUS MOLLUSCA OF JAMAICA. 



THE great number of species is remarkable. A few miles of coast, 

 without the aid of storms, and without dredging, yielded 420 species. 

 In the small bay of Port Royal, 350 marine species were found. A 

 pint of sand, taken from a surface 3 yards long, contained 110 species. 

 Probably there are 350 or 400 specimens of land shells, and two or 

 three times as many of marine species. Extensive districts occur, 

 however, which are nearly destitute of land or marine shells. They 

 are accumulated in favorable stations. 



The difference in the extent of the distribution of the marine and 

 of the terrestrial species is remarkable. A majority of the marine spe- 

 cies are known to occur in the other islands; probably not more than 

 10 or 15 per cent, of them will be found to be peculiar to Jamaica. 

 But of the land shells, 95 per cent, are peculiar to the island. The 

 limited distribution of the terrestrial species is remarkable. A few 

 are generally distributed, but a large number are limited to districts of 

 a few miles in diameter, and several, although occurring abundantly, 

 could be found only within the space of a few rods. Only 17 fresh- 

 water species were found. Favorable stations for fresh-water species 

 are rare. 



In respect of the number of individuals of Mollusca in Jamaica, as 

 compared with more northern latitudes, the rule so obvious in the class 

 of fishes is not applicable to the same extent. Of fishes, the species 

 are much more numerous, but the individuals much less so. Of the 

 Mollusca, the total number of individuals is about the same as in this 

 latitude, and the number of species represented by a profusion of indi- 

 viduals is about the same. But the number of species not occurring 

 abundantly is much greater, so that the average of individuals to all 

 the species is less than in this latitude. From a comparison of the 

 laws of distribution of the marine and terrestrial species in the An- 

 tilles, it follows that the number of the latter must exceed that of the 

 former. With the insular distribution of the terrestrial species may be 

 associated the fact, that the coral reefs are all fringing, for both facts 

 are connected with the geological fact, that these islands are in a pro- 

 cess of elevation. Prof. Adams before the American Association. 



