1872.] SENATE— No. 249. 31 



already, for the sake of convenience provisionally separated 

 into sub-divisons, answering in a general way to the three above- 

 named eras. So the aim has been to separate the Secondary 

 material into two distinctly recognized parts ; 1st, the Triassic, • 

 and 2d, the Jurassic and Cretaceous, the line of division 

 between the two last-named eras being by no means yet exactly 

 drawn. Still, in this instance also, for the sake of convenience, 

 as the work has gone on, the Jurassic and Cretaceous fossils 

 have been, for the most part, provisionally separated into two 

 sections. 



A further step in the work of arrangement has been 

 attempted ; viz., the disposition of all the material in each of 

 these horizontal sections, according to zoological relations. To 

 take a single case as an illustration : having separated the fossils 

 of the lower Silurian age from those of the upper Silurian, I 

 aimed to arrange them according to orders, beginning with 

 Polyps, and proceeding upward by regular gradations to the 

 highest forms represented in this portion of the collection. I 

 did the same with the Taconic fossils, and with the upper Silu- 

 rian. A similar work is in progress, and has been carried for- 

 ward to a very considerable extent on the fossils of each of the 

 other great geological eras. 



In order to aid the memory, and to serve other purposes, 

 these materials have been, so far as circumstances would allow, 

 arranged in each room in regular sequence — the succession of 

 life in time being, in a measure, represented under relations of 

 space. For instance, in the Palaeozoic room, one may start 

 from the Taconic, in a remote corner, and pass to the lower 

 Silurian, the upper Silurian, the Devonian, the Carboniferous 

 and the Permian, advancing from lower to higher, by successive 

 steps. Nor is this all : a like ascending sequence may be already 

 observed in the arrangement of zoological orders, and even of 

 many minor divisions of the orders. The same thing is true of 

 the arrangement in the Mesozoic and Tertiary rooms. 



The material set apart for exchange is also receiving its share 

 of attention. 



The statements which have been made may serve to give some 

 general impression of the work attempted, and already in many 

 respects well advanced. Indeed, it has been carried out, in 

 some instances, more minutely than indicated. Of course, the 



