552 GEOLOGICAL MEMOI11S. 



The plutonic rocks of the district under discussion consist of 

 granite, syenite, quarziferous porphyries, eurites and melaphyres, the 

 mutual relations of which, though often difficult to make out, seem 

 to lead to important conclusions with reference to the sedimentary 

 deposits, almost all of them in fact being more modern than 

 these latter, and proving, by their relations with the metamor- 

 phic rocks, that none of the igneous rocks of the Altai are in 

 the strict sense of the word " primary," or in other words, portions 

 of the original solidified crust of the globe. 



Rocks of mechanical origin occupy the greater part of the Altai 

 district, and with the exception of some diluvial deposits, they all 

 appear to belong to the older or palaeozoic series. I have been 

 able to determine positively the following groups, viz. : — a. De- 

 vonian formations ; (d. carboniferous limestone; and y. uppermost 

 beds of the coal measures or possibly of the Permian series. 



a. Devonian Mocks. Rocks of this period (so far as my inves- 

 tigations, limited certainly to a small part of the whole area occu- 

 pied by them, enabled me to judge) are distributed in three regions 

 separated from one another by other ancient but non-fossiliferous 

 strata, or more frequently by granitic rocks and diorite. These 

 three regions I have designated the basin of Zinieff, that of Tomsk, 

 and that of the river Yenesei, extending between the mouth of the 

 Ambakaya and the town of Krasnoyarsk. From the two first of 

 these I obtained fossils, of which the following is a list, viz. : — 



Calymene macrophthalma Cyathophyllum turbinatum Goldf. 



Terebratula prisca var. explanata C. hexagonum 



T. resembling T. ventilabrum C. helianthoides? 



Spirifer speciosus C. quaclrigeminum ? 



S. alatus Petraia ccltica Londs. 



S. resembling S. Verneuili Calamopora fibrosa Goldf. 



Leptaena, resembling L. lata C. spongites 



Orthis crenistria C. polymorpha 



Produeta subaculeata C. infundibuliformis 



Stromatopora concentrica Retepora retiformis. 



together with numerous fragments of Orthoceratites and stems of 

 encrinites. 



/3. Carboniferous Limestone. The carboniferous like the De- 

 vonian rocks are grouped in three detached basins, from each of 

 which I have obtained fossils more or less characteristic. The 

 fossils obtained from these basins are the following : — 



Orthis arachnoidea Produeta punctata 



Spirifer mosquensis P. resembling punctata 



S. trigonalis Retepora membranacea Phil. 



S. Bronnianus R. retiformis 



Produeta antiquata Eschara scalpellum Londs. 



conjectures founded on the parallelism, or supposed parallelism, of the Altai, with 

 other known mountain chains. From an answer to an observation made by 

 M. de Verneuil, in the course of the subsequent discussion (also recorded in 

 the " Bulletin") it appears that these conjectures are hardly sufficiently gi'ounded 

 to satisfy even the author himself. — Ed. 



