196 William Davies — On the ExJmmation of Omosaurus. 



whicli divided it into three nearly equal parts ;^ these again, when 

 the work of development was far advanced, were fixed and joined 

 together in a frame, and now present the appearance of an entire 

 slab. 



And now commenced the principal work, that of cutting away 

 the upper surface of the block, and tracing the imbedded bones, 

 for as yet, with the exception of the femur already mentioned, and 

 some centra of vertebrse, it was not certainly known what parts of 

 the skeleton the stone enclosed. This was a work of much labour, 

 patience and skill, for the matrix was hard and adhered firmly to 

 the bone, which, being much softer, rendered it almost impossible 

 to remove the former, without also taking away the surface of the 

 latter. However, slowly but satisfactorily the work progressed, and 

 bone after bone was brought to light, until a grand group, comprising 

 the iliac bones of either side with the sacrum entire and retaining 

 their normal form and position, an ischium, femur, dorsal, and caudal 

 vertebrse, were projected in bold relief from a background of grey 

 stone : forming a magnificent fossil group unique of its kind (Plate 

 VIII. Fig. 1). This work was skilfully executed by Mr. Barlow, 

 the mason attached to the Geological Department, and occupied 

 him several months. But happily the labour has added much to 

 palasontological knowledge, as witnessed by Prof. Owen's Mono- 

 graph already referred to, and the results have been a source of 

 gratification to those who took part in its reconstruction. 



In addition to the bones above mentioned, a large dermal spine, 

 several centra and processes of many vertebra, chevron-bones, por- 

 tions of ribs, and numerous fragments of other bones, had been 

 found and taken up by the workmen, before the larger bones were 

 exposed, and these fragments unquestionably prove that many, if 

 not most of the vertebrse were lying around the central mass, and 

 also lead to the inference that, had some competent person been 

 present at the moment of its first discovery, a much larger portion of 

 the skeleton would have been secured ; for undoubtedly many a fine 

 fossil is lost to science through the general ignorance and careless- 

 ness of the workmen, and the strong propensity on the part of the 

 public to carry oE portions of any curiosity for the mantel-shelf! 



In the same workings have also been found remains of Fliosaurus, 

 Plesiosaurus and vertebras of a new species of Bothriospondylus (B. 

 suffossus, Owen), the latter of which are described in the Monograph 



1 Tke surfaces of these cracks were completely covered with a felting of the root- 

 lets of plants, which had penetrated through some eight or nine feet of compact clay to 

 this nodule, and had long fed upon and derived nourishment from the decayed bones 

 of the old monster within it. At least I assumed this much from the fact, that I had 

 all the other nodules broken up to see if they contained any bones, and although 

 they were much cracked, in none were there any traces of rootlets ; nor did I find in 

 one of them any organic remain which could have served as a nucleus of concretion. 

 The form of each was elliptical, more or less elongated, and they were large, measur- 

 ino- several feet in their long diameter, and were traversed by veins of crystalline 

 calcite, having also large cavities and fissures lined with crystals of the same mineral. 

 The nucleus of all these nodules of septaria was probably organic, but may have 

 consisted of more perishable organisms than bones, and so have been slowly dissolved 

 and removed, leaving the cavities lined with spar to mark their former presence. 



