80 Reviews — Dr. Rued — Jurassic Radiolaria. 



that they flourished as abundantly and in as great variety of form in 

 the seas of these periods, as in those of Tertiary and recent times. 



From the Middle and Upper Chalk Dr. B,iist discovered but few 

 Radiolarians, they were however abundant in Neocomian limestone 

 at Urschlau in Upper Bavaria. The so-called Aptychus-Schiefer from 

 Urschlau and several other places in the Tyrol were found to be very 

 rich in well-preserved specimens. They also occur in the Jasper and 

 Chert from rocks of "Tithon" age in the Upper Alpine Jura at 

 Allgau, near Murnau, and other places iti the Tyrol. In the red 

 jasper the Eadiolarians are so abundant that their shells are in close 

 contact in the rock, whilst in the chert on the other hand they are 

 comparatively rare. In this latter material the Radiolarians are re- 

 placed by sponge-remains and foraminifera, and many dark beds of 

 chert are stated to consist of bedded masses of scattered sponge- 

 skeletons (in the same manner as turf consists of remains of 

 Sphagnum), with a few scattered Radiolaria between. The red jasper 

 however, may be compared to a Radiolarian mud, like that brought 

 up from the greatest ocean depths by the Challenger expedition. 



Fragments of this jasper, containing the same species of Radiolarians, 

 are found in gravels all over West Switzerland, and they are most 

 abundant in the Nagelfluh of the Rigi and the conglomerate of 

 Uetliberg. 



In Hungary also, in chert and jasper of the age Of the Tithon, the 

 Malm, and the Middle Dogger, Radiolarians were discovered. 



The author obtained his richest harvest of Radiolarians from 

 Coprolites occurring mingled in beds of iron ore, which are largely 

 worked at Usede, near Peine, in Hanover. 1 The ore-deposits rest on 

 Gault-clay and are overlaid by Cretaceous marls, but neither in the 

 rocks above nor in those below were Radiolarians discovered. The cop- 

 rolites in these beds are round or cylindrical in form, and vary from the 

 size of a lentil to that of a goose's egg, they are largely employed for 

 making superphosphate. The age of these coprolites was determined 

 by the occurrence with them of two species of Ammonites ; one, 

 A. torulosus, Zieten, characteristic of the Lower Dogger, and the 

 other, A. caprinus, Schlot., of the Upper Lias. The author investi- 

 gated coprolites from the Lias of Lyme Regis and Gloucester, which 

 corresponded closely in character with those from Usede, but only in 

 those from Gloucester were some few Radiolarian remains discovered. 



Further, in red limestones of Middle Lias age, and in Chert of the 

 Lower Lias in Hungary, Radiolarians were also present. 



The author calls attention to the fact that whilst in Jurassic and 

 Tertiary strata a Radiolarian-fauna is so largely developed, in the 

 intervening Cretaceous beds hardly a dozen species have been found, 

 and it seems also to be a general rule, that where sponge-remains 

 and foraminifera are abundant, Radiolarians are of rare occurrence, 

 and vice versa. 



1 The geological horizon of these coprolitic iron-ore heds appears to he the same 

 as that of the Cambridge Greensand; and it is worthy of notice tbat Radiolarians 

 have been discovered by Prof. Sollas in the Coprolites of this latter deposit, but they 

 have not yet been described. See Quart. Journ. Geol. Soc. vol. xxix. 1873, p. 78. 



