180 MR. A. RENDLE SHORT ON RH^TIC [May I904, 



to the Continent, it is often absent at intermediate places, as at 

 Droitwich (27), Stoke Gifford, and locally at Aust and Penarth. 

 The conditions, therefore, to which it is due, were operative over a 

 wide area, but only in certain parts of that area. 



An interesting feature is the frequency with which the Bone-Bed 

 occurs in pockets on a flat surface, or spread out over that surface. 

 I have already described its occurrence in this way spread out on, 

 and closely cemented to, a planed-off surface of upturned Carbon- 

 iferous-Limestone bands at liedland (Bristol). At Penarth I found 

 it lying in pockets on a surface of hard, tea-green, calcareous marl- 

 stone, which has been worn into irregular hollows and ridges in a 

 way that suggests contemporaneous erosion. Here it contains, 

 besides teeth and scales, fragments of rolled marl, more or less 

 rounded pebbles of Carboniferous Limestone (sometimes as much 

 as 2 inches in diameter), pebbles of quartzite up to 1 inch in 

 diameter, and small well-rounded quartz, occasionally black on 

 fracture. The organic remains are not often entire, unless quite 

 small ; the larger fossils have usually been broken up. This deposit 

 has also been noted by Storrie (32). At Chipping Sodbury, again, 

 the Bone-Bed occurs in pockets in a surface of Carboniferous-Lime- 

 stone bands that have been upturned and cut off flat, and here also 

 I found pebbles of Carboniferous Limestone embedded in the Bone- 

 Bed. There are, as well as these, smaller pebbles of hard sandstone 

 from the arenaceous bands in the Upper Limestone Series, which are 

 exposed quite near. 



It is well known that at Aust, too, the Bone-Bed includes rolled 

 pebbles of marl, etc. The true Emborough Bone-Bed, described by 

 Profs. Lloyd Morgan & Reynolds (48) under (e), contains more 

 pebbles than teeth ; it is a closely-packed, rather loosely-cemented 

 conglomerate full of pebbles, usually about the size of a pea, chiefly 

 consisting of rolled Carboniferous Limestone, but also of chert and 

 quartz. 



Pebbles are also recorded in the Bone-Bed at Garden Cliff, where 

 I take it that the lower, though less conspicuous band, is the 

 true Bone-Bed, and at Bourne Park (54). They are often men- 

 tioned in Continental records also, as, for example, in Lorraine, at 

 Hildesheim, etc. (62). 



The conglomeratic nature of the Bone-Bed, however, has frequently 

 been noticed, and further examples are not necessary. 



In the Bone-Bed certain fishes tend to preponderate locally. At 

 Aust it is Ceratoclus that, although not now abundant, is yet the 

 prominent feature. At Redland, Acrodus minimus is most abun- 

 dant, though Saurichthys and Gy role pis follow closely. At Chipping 

 Sodbury it is Saurichthys, and at Penarth Sphcerochis minimus 

 that is most prominent. Ceratoclus is fairly common at Chipping 

 Sodbury. 



Now, we may ask, what were the conditions under which the 

 Bone-Bed was laid down ? 



I. They must have been conditions of extensive and shallow 

 water, or of flats just above water-level. This is proved by 



