182 ME. A. REXDLE SHORT OX EH^TIC [May I904, 



An interesting modern analogy has been described by Leith 

 Adams. 1 In September 1867 a violent storm killed such numbers 

 of fishes in the Bay of Fundy, by driving them into shallow water, 

 that the coast was in places covered with their bodies to the depth 

 of a foot. 



Raised by the storm, the waters overflowed most of or all the 

 mud-flats, scattering pebbles from the Carboniferous Limestone 

 and other beaches of the old Keuper lake. These pebbles had, of 

 course, been rounded long before on the beaches, and the storm 

 merely spread them out over the flats. 



We may here notice the abundance of small rounded quartz-pebbles 

 that are often recorded in the Bone-Bed. I have found them at 

 Eedland, Aust, Chipping Sodbury, Penarth, Emborough, etc., and 

 they frequently occur elsewhere. They are often observed far away 

 from any quartziferous rocks, apart from any other siliceous pebbles. 

 They are seldom more than half an inch in diameter, and are 

 usually smaller, but are seldom smaller than hemp-seed. They are 

 fairly well-rounded as a rule, and if angular the sharp edges have 

 always been just blunted. They usually have a peculiar resinous 

 appearance. 



These quartz-pebbles frequently occur under similar conditions 

 in Germany, and were thought by Quenstedt (56) to have been 

 swallowed by Ichthyosaurus and other vertebrates for digestive 

 purposes. My attention was first called to this hypothesis by Mr. 

 A. Vaughan. Quenstedt succeeded in demonstrating them in the 

 position of the stomach, inside an Ichthyosaurus-skeleton. Such an 

 explanation fits in well with their peculiar distribution, referred to 

 above. The characteristic surface and the rounding-off of the edges 

 would be very likely under such circumstances. But the most 

 important proof of the theory, to my mind, was furnished when I 

 noticed their abundance on the surface of the argillaceous limestone 

 numbered 18 at Aust, which is covered with Pleurophorus elongatus, 

 fish-remains often large, slender and yet perfect, coprolites, and 

 these quartz-pebbles, but no others (see p. 179). The bed is not in 

 the least conglomeratic — in fact is fine-grained, and nevertheless 

 these pebbles, of this particular description only, are found with 

 the fish-remains on the surface. They cannot possibly have been 

 washed there by water ; they must have been dropped. 



I need scarcely say that all the pebbles in the Bone-Bed did not 

 have such an origin. Angular pebbles of limestone are frequent, 

 which could never have survived a passage through an animal's 

 alimentary canal. Moreover, the Carboniferous-Limestone and 

 siliceous-grit and marl-pebbles are generally much bigger, and more 

 irregular in size and shape, than the quartz-pebbles ever are. 



(c) The Black Shales. — These are very constant, and too well 

 known to need description. 



In the Bristol district there is always a zone of very firm, well- 



1 Quart. Journ. Geol. Soc. vol. xxix (1873) p. 303. 



