C. E. de Ranee — Glaciations of the Lake District. 107 



a valve of DitJiyrocaris f most beautifully sculptured, which we have 

 figured on Plate III., Fig. 5, of the natural size. The specimen is 

 eleven lines in breadth, and probably measured, when entire, nearly 

 two inches in length. The dorsal border is rounded in a corre- 

 sponding degree with the ventral border ; a small rostrum is observ- 

 able at the anterior end, from which two prominent ridges also take 

 their rise and pass over the side, one arching towards the dorsal, the 

 other bending towards the ventral line, but uniting again on the 

 centre of the valve at one inch from the anterior end. The fine 

 strige above and below these prominent ridges are parallel, but those 

 inclosed in the central elliptical space cross one another so as to 

 form a finely reticulated pattern on its surface. The eye-spot is dis- 

 tinct and prominent at the anterior end, near the intersection of the 

 two curved ridges. Other slight, scarcely visible, folds traverse the 

 carapace parallel to the ventral and dorsal border, indicating that 

 the original shell was of extreme tenuity, like that of the recent 

 Apus and Estlieria. 



Should the discovery of other and more perfect specimens prove 

 this to be a true Bitliyrocaris, it will be the first specimen of this 

 genus met with in rocks of Devonian age. 



I had proposed to call this form D. striatus,^ but as there is already 

 a D. tenuistriatus, it will be better not to give it so indistinct a na,me. 

 I therefore beg to name it Bitliyrocaris ? Belli, after its discoverer. 



IV. — On the Two Glaciations op the Lake District.'^ 

 By C. E. de Eance, F.G-.S., of the Geological Survey of England and Wales. 



IT has always been difficult to account for the fact that, while 

 Moraine Drifts occur at such low levels in the Lake District, 

 Marine Drifts are found at such high elevations in the surrounding 

 district. Mr. Mackintosh's new facts throw some light on this phe- 

 nomena, but do not entirely explain it, owing to his having given, in 

 my opinion, far too little importance to the second Glaciation expe- 

 rienced by the Lake District after its emergence from the Glacial Sea. 



His discovery of Boulder-clay and Laminated Sand at several 

 points in the Lake District, though invaluable as proving the sub- 

 mergence of the mountains, are in themselves only fringes, patches, 

 or terraces, the remains of masses of Marine Drift which once filled 

 up the valleys to considerable heights, which, with the exception of 

 these fragmentary portions, have been entirely scooped out by the 

 glaciers of the second age, which left their marks and their moraines 

 not only in highland valleys, as admitted by Mr. Mackintosh, but in 

 such lowland valleys as the Liza, Windermere, and Langdale, often 

 in the actual space cleared out of the Marine Drift and the still 

 older Lower Moraine Drift beneath, 



I have elsewhere^ endeavoured to show that two distinct Lower 



1 British Association Eeports, Section C, Liverpool, 1870. 



'^ I have merely visited the district as a tourist. 



3 "Glac. Phen. of Lan. and Ches." Quart. Jouru. Geol. Soc, Dec. 1870. 



