308 Professors Rupert Jones and W. K. Parker — 



those which have been carefully examined by geologists, is almost 

 without a parallel in respect of the features of interest which it 

 affords, I may refer to two points of some novelty which came under 

 my notice. Occasionally, in consequence of the extreme pressure, 

 the obsidian on the sides of the dykes has assumed a most remarkably 

 fibrous structure, such as has not, so far as I am aware, been observed 

 in this rock at any other locality. A second curious fact was one 

 which I was struck with in breaking up some of the great masses of 

 obsidian, namely, that the bright glassy surfaces of fracture only 

 endured for a few seconds after their exposure ; a delicate white film, 

 doubtless due to the exudation of some crystalline matter on their 

 surfaces, being formed upon them actually under the eye of the 

 observer. 



(To be concluded in our next Number.) 



IV. — Lists of some English Jurassic Foraminifera. 

 By Professors T. Eupert Jones, F.E.S., F.G.S., and W. K. Parker, F.E.S., F.Z.S. 



THE late Professor John Phillips requested us to draw up, for an 

 Appendix to his new edition of " The Geology of Yorkshire," a 

 generic list of the Foraminifera of the English Oolites. He had him- 

 self, indeed, supplied us with some good material from the clays near 

 Oxford. We have noted the following Foraminifera^from the Lower 

 Oolite, Oxford and Kimmeridge Clays, and the Portland Limestone, 

 in our collection. 



The Foraminiferal Fauna here indicated is comparable with that of 

 Switzerland, reviewed at p. 213, Vol. X. Geol. Mag. (May, 1873), 

 though not so rich in Miliolce, and wanting some other genera. 

 M. 0. Terquem's still more richly illustrated memoirs on Oolitic Fora- 

 minifera (Metz, 1867-70), place before the eyes an enormous collec- 

 tion of similar Microzoa; 1 and the Eev. J. F. Blake's memoir on the 

 Kimmeridge Clay, lately read before the Geological Society of Lon- 

 don, enumerates numerous forms of the same group. 2 



1. Upper Portland Limestone, Eidgeway, Dorset. 



Lagena globosa. 

 Cristellaria rotulata. 



Trochammina (combining the characters of Tr. gordialis and Tr. incerta ; low- 

 conical, having irregular chambers within annular chambers, sub-translucent). 



2. Kimmeridge Clay, Aylesbury. 

 Fora?ninifera. Cristellaria. 

 Glandulina. Planidaria. 

 Nodosaria. Lituola (nautiloid). 

 Dentalina. 



Vaginulina (V. harpd). Polyzoon: — Lepralia. 



Marginulina. 



3. Kimmeridge Clay, Kimmeridge, Dorset. 

 Lagena (L. globosa, var., simple, oval, Cristellaria. 



without neck). Pulvimdina (P. caracolla). 



Lingulina. Texlularia [Plecanium ; small, long, 

 Dentalina. rough). 



Vaginidina (V. harpa). Litnola (straight). 



Margimdina. Trocham?7iina incerta. 



1 See also Annals Nat. Hist, series 4, vol. viii. pp. 363-365. 



2 Quart Journ. Geol. Soc. vol. xxxi. p. 222. 



