86 On the Fundamental Types of Organization. 



to the sloth, the other from the bear to the opossum. Farther 

 inquiries would likewise disclose other intermediate series. Such 

 interruptions of the principal series are, however, quite corres- 

 pondent to the laws of natural affinity. They would only 

 transgress these if interposed members gave rise to recurrent 

 series in one of the two principal ; if, for instance, an animal 

 which, according to its natural affinities, succeeds to the sloth, 

 should, from the proportion of its brain and spinal cord, stand 

 above it. But I do not believe that such a genus can be found. 

 As every genus and species, not only of the mammalia, but 

 also of the other vertebrated animals, has a certain proportion 

 between its brain and spinal cord, in the same manner each part 

 of the brain, especially the cerebellum, bears a definite propor- 

 tion to the other parts. Hence we might deduce further speci- 

 fic and generic marks ; and one day we may be able to distin- 

 guish the whole of the vertebrata by the numerical masses and 

 dimensions of the parts of the encephalon, and range them from 

 this character according to their natural affinities. The relation, 

 it is true, varies in different individuals of each species, but there 

 are limits which it never exceeds. 



Analysis of the Lahradorite Felspar found in the Trap-Rocks 

 (yf Scotland. By Captain Le Hunte. Communicated by 

 the Author. 



99.193 



The specimen analyzed was found near Campsie, in a por- 

 phyritic greenstone. It was in the form of long narrow crys- 

 tals, nearly transparent and colourless, of a foliated structure, 

 and vitreous lustre. Its specific gravity was 2,689. . The larger 

 crystals frequently present a flat conchoidal fracture, which first 



