58 J. R. Dakyns — Some Snowdon Tarns. 



The tail and hinder part of the trunk present the right lateral aspect 

 to view, but the remainder of the body lies squarely on the ventral 

 surface and is flattened out symmetrically on both sides by pressure. 

 The fins are superbly preserved, and with their bundles of finely 

 articulated rays and fringe of biserial fulcra make a striking appear- 

 ance. The total length of the fish is 1-7 m., of which the head forms 

 about 0*5 m. In point of size, relative length of head, fin-structure, 

 and squamation, there is a very close resemblance to the recent 

 Alligator gar, or L. viridis, Giinther ; the dentition is much the 

 same, and the number of longitudinal and transverse scale-series 

 is the same in both. A detailed description of the new specimen 

 will form the subject of a separate paper ; it will be sufficient for 

 the present to point out that the modern gar, and more particularly 

 the Alligator gar, has existed from at least Eocene times essentially 

 unchanged. 



EXPLANATION OF PLATE IV. 



Gallinuloides Wyomingensis, gen. et sp. nov. Middle Eocene : Fossil, "Wyoming. 

 c, eoracoid ; cl, furculum ; /, right femur; h, h\ humeri of left and right 

 wings respectively ; i, ilium ; m, manus ; p, pubis ; r, radius ; rb, detached 

 rib ; s, scapula ; st, sternum ; t, tibia ; tm, tarso-metatarsus ; u, ulna ; 

 I-IV, toes. 



III. — Some Snowdon Tarns. 

 By J. E. Dakyns, Esq. 



I HAVE from my boyhood been intimately acquainted with 

 Snowdon and its neighbourhood, and for some years past 

 I have been investigating the geology of the district in a systematic 

 manner. In doing this I have paid particular attention to the lake 

 basins, and shall in the following pages give an account of some of 

 my investigations as far as they have gone. I say as far as they 

 have gone, because I hope in the future to make by means of a level 

 more accurate measurements than can be made with a pocket 

 aneroid ; and I also hope that next Summer the lakes and tarns will 

 be sounded either by myself or by someone else ; for at present we 

 know nothing about the depth of Llyn dur Arddu, next to nothing 

 above that of Glaslyn, and very little about Llydaw, though that 

 little is of great importance. 



I will now proceed with my account. Glaslyn at its outlet is 

 bounded by rock on the north side and by drift on the south, but 

 the shape of the ground shows that the drift is merely a mound of 

 no great thickness, banked against the Gribbin, as the rocky spur 

 is called which separates Glaslyn from Llydaw. At a distance of 

 about twenty yards from the lake solid rock is seen in the bed of 

 the outflowing stream at less than six feet below the level of the 

 lake. This to my mind proves without any reasonable doubt that 

 the lake lies in a rock basin; for, as I said above, the drift is 

 apparently of but little thickness, and the lake is certainly more 

 than six feet deep : I have myself dived into it to a greater depth 

 than that. I will not, however, insist upon this ; for at the old mill, 

 seventy yards from the lake, solid rock extends rigid across the 



