344 The Future of Geology. 



fluid series, the former coinciding with the radiate and articulate 

 class, and joining the Vertebrata through the Crustacea ; the latter 

 running parallel with the Molluscan order, and connecting itself to 

 the Vertebrata through the Cephalopods. 



The fluids of the zoophytic series are invariably corpusculated, 

 but the corpuscles cannot yet be reduced to any definite type of con- 

 formation. In the Medusan series, these bodies become more de- 

 finitively organised. The author then demonstrates, that through- 

 out the whole radiate and articulate classes, wherever it is found, the 

 chylo-aqueous fluid is richly corpusculated, or in other words, charged 

 with floating morphotic elements, which, from the constancy of their 

 characters in different species, become grounds for specific distinc- 

 tions. It is stated, that, throughout the Echinoderms, Entozoa, and 

 Annelida, in which, even in the adult animal, the blood-proper and 

 the chylo-aqueous fluid, though separate, coexist, the latter fluid only 

 is corpusculated, the true blood being invariably limpid and perfectly 

 fluid (incorpusculated), and almost always the seat of the colour, 

 the latter existing as a substance dissolved in the fluid : while in no 

 instance does colour develop itself in the chylo-aqueous fluid. 



The paper then shews, that at the point where the chylo-aqueous 

 system disappears, namely, at the Myriapods, the true blood be- 

 comes the vehicle of the corpuscles. 



And lastly, the author adduces a great variety of observations in 

 confirmation of the statement, that throughout the whole Molluscan 

 series without exception, coinciding with his " single-fluid series" 

 the fluids are richly charged with corpuscles. 



• 



The Future of Geology. 



A system in Geology is like a genus in Zoology and Botany, — an 

 arbitrary division for one person, an attempt to express a natural group 

 for another and more philosophical head. It is consequently a term 

 of very different value in the writings of one geologist, to that which 

 it enjoys in the works of another. What one calls a formation, his 

 neighbour calls a system. Yet each, if he be aiming, as we presume is 

 the purpose in most instances, at the establishment of a natural group 

 in time, is really treating of the same order of thing, with a differ- 

 ence only in degree. It would be desirable, doubtless, that we should 

 have one uniform terminology ; but the ago is not ripe for such an 

 invention yet. We are working towards it, but must not hurry. An 

 idea is gradually being evolved out of the efforts at the discovery 

 and defining of geological subdivisions. It is the idea of fades. The 

 faunas and floras that have succeeded each other, interlacing in their 

 succession, during the course of geological ages, exhibited from time 

 to time peculiar combinations of forms, affinities, and analogies, which, 



