592 JOURNA.L, BOMBAY NATURAL HIST. SOCIETY, Vol. XXVII. 



'.good state of preservation. In general they must have lain undisturbed where 

 the dead body dropped except for slight movements caused by the moving 

 waters. This has caused them to assume various positions. There do not 

 seem to have been any fishes or aquatic animals, at least in the shallow waters 

 where the frogs were living, that fed on the carcasses considering the fact that 

 the skeletons are complete. Out of hundreds of specimens examined by me 

 there is only one where the femur is separated and is lying parallel to the tibia 

 and another in which the foot is detached. It is true that very often what 

 appear to be fragments of skeletons are met with but these are due to the skeleton 

 being buried in different layers of the shale which in splitting carry only a part 

 of the skeleton. 



The fossil impressions occur in various conditions. Sometimes it is only a 

 blurred outline that is left on the shale as if the dead batrachian had been 

 covered over by the earthy sediment before the skeleton had been denuded 

 of the flesh ; at other times it is a clear picture as if drawn by a pencil that 

 is left on the stone. This condition was probably brought on by the shale 

 being subjected to very great pressure by the effusion either of the lower or 

 the upper traps causing the mould of the fossil to flatten out. More often it 

 is merely a mould that is left on the shale, the skeleton having been completely 

 removed and the space left unfilled by any sediment or mineral. The hollow 

 is some times fiUed by a yellowish deposit. It is only rarely that a fine 

 casting of the bones especially of the lower extremities is obtained. This ' 

 condition, however, I am inclined to believe, is more general than is usually 

 found, the reason for its occurrence being that the skeleton is encased between 

 two layers which do not split at the skeleton but remain adhering to one of 

 the pieces of the shale. Thus one-half of the shale shows the fossil in relief 

 while the other carries a corresponding depression. It may often happen 

 that if the layers split accurately at the skeleton the core is shaken off and 

 lost, leaving only a mould on both pieces of the split shale. In the few 

 instances where the core is exposed, it is found to show the minutest details 

 of the bones. 



The specimens of frog fossils submitted to Prof. Owen seem to have been of 

 a uniform size of about half an inch. As Dr. Carter's paper embodying Prof. 

 Owen's description of the fossil is not very easUy accessible, I may be allowed 

 to repeat it here : 



" The portions of the shale transmitted by Mr. Clarke contain delicate but 

 for the most part distinct traces of the generally entire skeleton of small 

 anourous Batrachian, the osseous substance is black, as if charred. 



The number of the vertebrae, atlas and sacrum inclusive, is nine ; the caudal 

 vertebrae are fused into a long, slender, cylindrical style, as in most anourous 

 Batrachia. 



In the specimen which lies on its back, the posterior convexity of the 

 vertebral bodies are shown. 



The short sub-cylindrical, and very slightly expanded lateral or transverse 

 processes of the sacrum, and the absence of ribs or their rudiments in the dorsal 

 vertebrae, with the proportional expanse of the skull and length of hind legs, 

 show the specimens to belong to the family of Frogs (Banidce). 



There are seven abdominal vertebrae with long and sub- equal transverse pro- 

 cesses, that of the second (third vertebra including the atlas) being the longest. 

 The humerus is cylindrical, not expanded as in Cystigranathus. The head 

 is little larger relatively than in Rana temporaria, Bana esculenta or Hyla viridis 

 and still larger therefore in Toads and Natterjacks (Bufonidse), or than in the 

 Pipa. The expansion of the sacrum removes the genus Pipa and the Bombin 

 atores from that of the present fossils. The following are the measurements 

 f the more perfect specimens : — 



