180 Scientific Intelligence — Zoology. 



the chymiferoiis circulation. Animals having this circulation, have no 

 true respiration. They have only tubes to distribute freshly aerated 

 water to different parts of the body. — Proc. Bost. Nat. Hist. Soc. 



13. Distribution of the Testaceous Mollusca of Jamaica. — The 

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

 out the aid of storms, and without dredging, yielded 450 species. 

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

 A pint of sand, taken from a surface three 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 dis- 

 tricts occur, however, which are nearly destitute of land or marine 

 shells. They are accumulated in favourable stations. 



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

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

 species 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 dis- 

 tricts of a few miles in diameter ; and several, although occurring 

 abundantly, could be found only within the space of a fQvf rods. 

 Only seventeen fresh- water species were found. Favourable 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 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 individuals is about the same. But the number of species not 

 occurring abundantly is much greater, so that the average of indi- 

 viduals to all the species is less than in this latitude. From a com- 

 parison of the laws of distribution of the marine and terrestrial 

 species in the Antilles, it follows that the number of the latter must 

 exceed that of the former. With the insular distribution of the ter- 

 restrial 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 process of elevation. — Professor Adams 

 before the American Association. — American Annual of Scientific 

 Discovery, p. 334. 



14. Metamorphoses of the Lepidoptera. — Professor Agassiz said 

 that he had, during the past season, been studying the metamor- 

 phoses of the Lepidoptera, and, to his great surprise, he had found 

 that one stage in the transformation of these insects has been over- 

 looked by naturalists. We knew the Lepidoptera in three condi- 

 tions,— that of the worm, furnished with jaws and jointed, the chry- 

 salis, and the perfect insect with four wings. The change not be- 



