notices of Memoirs — Big shy s Thesaurus Siluricus. 211 



part of the stage in ■wliicli it occurs, then, in a given order, its 

 author and locality, or localities, in the column indicative of its 

 proper stage. The " Thesaurus " contains 7553 species, and there- 

 fore gives abundant scope for profitable study ; but probably it does 

 not give the tithe of the whole Silurian life yet lying buried in the 

 wilds of the Arctic Circle, of Hudson's Bay, Labrador, the two 

 Americas, Scandinavia, Australia, India, etc. 



The author acknowledges many valuable corrections and sugges- 

 tions made by Messrs. J. W. Salter and Kobert Etheridge, who have 

 carefully gone over the manuscript : he has also received several 

 unpublished contributions relating to the Silurian Faima and Flora 

 from foreign Palaeontologists. In this brief account of the Thesau- 

 rus, the author gives numerous tables of the general results arrived 

 at. One table shows the number of species common to regions very 

 remote from each other, some of them being antipodal — a fact which 

 tells the more forcibly from the tenacity with which a large part of 

 Silurian life clings to locality as well as to horizon. Thus, 179 

 species are common to Europe and America ; 5 species to Europe and 

 Australia ; 6 species to America and Australia, etc. 



Another table gives a synoptical view of Silurian life, with special 

 reference to vertical range or reciu-rence. The orders vary greatly 

 in respect to recurrency. There is none among fossil fish. In 

 Cystidea it is only 3 per cent., in Gomophoceras, 5 per cent., and 

 is greatest in Strophomena, being 31 per cent. The author has 

 prepared a number of inferences in regard to recurrence. Among 

 which are the following : Species do not often change their horizon, 

 not even when placed in countries far apart ; the same species may he 

 typical of a single horizon in one country and recurrent in another ; the 

 number of recurrent species measures the amount of change in conditions. 



Respecting Extra-Epochal Eecurrence, the author states that 133 

 Silurian species may be regarded as recurring above the Silurian 

 beds ; with the exception of Chonetes sarcinulata, they all stop within 

 the Devonian period. The greater part of these recurrents are of 

 low rank : 20 are Brachiopoda, 11 Zoophytes, 1 Amorphozoon, 7 

 Gasteropoda, 3 Caphalopoda ; 1 Trilobite. 



These species are very migratory — few being found in two epochs 

 in the same country, but in different countries. 



[The Eoyal Society having voted £200 in the aid of the printing 

 of Dr. Bigsby's Thesaurus, we understand the veteran author intends 

 to incur the further expense (probably £300 additional) himself.] 



II. — Oligocene Deposit in Hungary. — At a meeting of the 

 Imp. Geol. Institute of Vienna, held on February 5th, 1867, M. de 

 Hantken read a paper on some Oligocene strata, exposed in a shaft 

 recently simk at Sarisap, near Gran, in Hungary. The strata, which 

 are of brackish and marine origin, attain a thickness of 156 feet. 

 The brackish beds, consist of sandy plastic clay, characterised by the 

 presence of Cerithium margaritaceum, Melanopsis ancillarioides, Cyrena 

 semi-striata, Desh., Eosalina Viennensis, d'Orb., and seeds of Chara. 



