7^ GEOLOGICAL MEMOIRS. 



witli forms most foreign to those now existing, whilst the tertiary fish 

 are very similar to recent forms. The Mammalia occur first in the 

 tertiary period, in any force at least, and commence as new classes of 

 animals with very bizarre forms. Thus, the mammals of compara- 

 tively late introduction are so very different from existing forms, 

 whilst the contemporary fish, representatives of a far more ancient 

 type, are with difficulty discriminated from their recent allies. This 

 also holds good with Insects. The tertiary Lihellulidce, Locustidce, 

 BlattidcB, Mycetophilce, TipulcE, Limnobice, &c. are very similar to 

 existing species, and at the same time belong to types that occurred 

 at an early period, and have passed down through many subse- 

 quent epochs. The ProtactidcB and the Bees, on the other hand, 

 appearing in the tertiary age, exhibit very singular forms. 



Thirdly, the oldest animal types of the present world appear also 

 to have the widest extension on the earth*. The limit, therefore, of 

 the dispersion of existing beings may afford at least some geological 

 hints. As examples, I will mention that the Fungus-flies appear 

 early in the Jurassic rocks, and that of these, one species {Myceto- 

 phila pulchella) occurred in the tertiary age, to which one species 

 found throughout Europe {M. 4-nofafa), and another found in North 

 America (31. cinctipes), have great resemblance ; also, that of the 

 genus Syrphus, a tertiary species is very similar to 8. scalaris, which 

 is spread throughout Europe, a part of America, and Asia ; and that 

 tertiary species of Limnohia occur which stand extremely near the 

 widely spread existing species ; &c. But however similar the fossil 

 species appear to be to the recent, they are, without exception, quite 

 distinct ; and the whole insect-fauna of the tertiary epoch is extinct ; 

 its fragments only, preserved to us by the rocks, give us a knowledge 

 of the peculiar life of the ancient world. 



[T. R. J.] 



On the Coal-formation near Meisdorf in the Selke Valley. 

 By Herr Giebel. 



[Sitzungs-Protoli. des naturwiss. Vereins in Halle, i. 1848-9, p. 29, and 

 Leonhard u. Bronn's Jahrb. f. Min. 1850, p. 91.] 



This formation, like those of Wettim and Lobejun, had been hi- 

 therto referred to the New Hed Sandstone. The trial-shafts, however, 

 in the Selke Valley have furnished the following characteristic plants, 

 that remove all doubt of these beds belonging to the true coal-for- 

 mation ; viz. Pecopteris arhorescens, P. abbreviata, P. OreopterideSy 

 P. polymorpha, Sphenopteris artemisicefolia, Neuropteris hetero- 

 phyllay N, auricidata, Annularia longifoliaj Lycopodites Bronni, &c. 



[T. R. J.] 



* [Count D'Arcliiac, M. De Verneuil, and Prof. E. Forbes have also enunciated 

 the fact, that the fossils common to the most distant localities are such as have 

 the greatest vertical range. Edinb. New Philos. Journ. vol. xxxvi. p. 325. — Ed.] 



