268 JOSEPH PEESTWICHj F.E.S., F.G.S., ON A POSSIBLE 



of large size, so common in some limestone districts, filled to 

 the brim Avith a breccia of limestone fragments, imbedded 

 in a red earth or loam, and generally cemented by calcite. 

 In this rubble, bones of extinct mammalia, and occasionally 

 land shells, are not unfrequently met with. The only 

 locality in England where these Ossiferous Fissures are 

 common, is the neighbourhood of Plymouth. On the shores 

 of the Mediterranean they occur in many places. 



The origin of these Ossiferous Fissures has been attributed 

 to the circumstance of rents in the rocks formed during the 

 Quaternary period ha^-ing been long left open. Into these 

 it was supposed that, from time to time, animals fell, as 

 they do now m similar unprotected pitfalls, or else that they 

 were driven into them when pursued by beasts of prey. 

 The washing in of the soil by streams and the fall of frag- 

 ments from the side rock were supposed to have gradually 

 filled the fissm-es. But there is nothing to show the presence 

 and action of streams, or to indicate that the process was 

 a long one. On the contrary, there are no icater-icovn 

 materials, and the bones are all in the same unworn con- 

 dition, nor do they show any of the ordinary effects of 

 weathering. Besides, had the bones been those of animals 

 trliich had fallen into the fissures, the entire skeletons of those 

 animals should be there, though the bones might be displaced. 

 So far from that being the case, the occurrence of an entire 

 skeleton is a rare and exceptional event. It is rare even to 

 find the bones of a single hmb in relative position. The 

 hones are dispersed icithout order, teeth largely predonn- 

 nating, and entire bones being comparatively scarce, whilst 

 broken fragments and splinters aboimd. These, I con- 

 ceive, are fatal objections to the explanation that the 

 bones are those of animals which fell into the fissures whilst 

 alive. 



The following list, the result of the collection made by 

 an early visitor to one of the Fossiliferous Fissm-es near 

 Plymouth, will serve to show the character of the animals 

 and the relative proportion and abundance of their bones. 



