138 Reports and Proceedings. 



it belonged to the Wealden ; while the presence of Kimmei-idge species might be 

 taken to prove that it was Kimmeridge. With regard to the so-called coprolites, 

 he remarked that it was difficult to assign those of the Red Crag, as well as those 

 of Cambridge, to their true position. He inquired how did the phosphatic nodules 

 originate ? Some observers maintain that they are rolled, but in the Crag the 

 sharks' teeth have nodules attached to their base, and these could not have been 

 acted upon by erosion. He thought the phosphates were derived either from 

 decomposed marine vegetation or from excrements. 



Mr. Price remarked that he had examined 75 or 80 species of fossils from the 

 Cambridge deposit in the Woodwardian Museum, and found that 33 per cent, 

 of them pertained to the Upper Gault. 



Prof. Seeley remarked that when he commenced the study of the question dis- 

 cussed in Mr. Jukes-Browne's paper, the fossils of the so-called Cambridge Upper 

 Greensand were very imperfectly known, and the prevalent belief among palaeon- 

 tologists was that the stratum represented the Gault. As the collections at 

 Cambridge were accumulated, and his acquaintance with English sections of 

 similar deposits was enlarged, he had enjoyed opportunities of discussing the 

 question with foreign palaeontologists, and now believed that the deposit essen- 

 tially represented the English Upper Greensand. He had noticed that the surface 

 of the Gault on which the Greensand rests is eroded, the phosphatic nodules being 

 spread uniformly, though the Vertebrate fossils were often contained in hollows of 

 the surface of the Gault. Occasionally the phosphatic bed was covered by a dis- 

 continuous dark-coloured clayey bed, divided from the Chalk Marl by a sharp 

 line of bedding. He thought that this band might result from denudation of 

 Gault, and the fact that it did not interfere with the continuity of the bed of 

 phosphatic nodules seemed to show that the denudation was local and of small 

 extent. The fact that sand was superimposed upon clay, necessarily implied an 

 upheaval of the sea-bottom, and therefore the newest-formed beds of the Gault 

 were sure to be denuded to some extent in consequence. But while this circum- 

 stance would explain the occurrence of a small per-centage of Gault species, it 

 rendered it rather improbable that so varied a fauna should have been derived 

 from a denuded portion of one stratum. Mr. Seeley's own investigations had not 

 led him to detect in the bed any preponderance of Gault forms . He further found 

 that the remains of Vertebrates in the Cambridge Upper Greensand were associated 

 series of bones, which would not be the case were they derived fossils, and that no 

 species of reptile had yet been identified as common to the Cambridge Greensand 

 and the Gault. He thought that the thinness of the Cambridge Greensand, as 

 well as the complex nature of its fauna, was only to be understood by considering 

 the circumstances of physical geography under which the deposit originated ; and 

 upon this some light was thrown by the thinness of the Kimmeridge Clay in the 

 same area, and by the occurrence of phosphatic nodules in that area in the so- 

 called Neocomian beds. These beds, like the Cambridge Greensand, contain 

 fossils derived from the Carboniferous Limestone and fragments of Palaeozoic 

 rocks, so that the phosphates might have been furnished to the sea in which the 

 deposit was formed by denudation of eruptive dykes of apatite, such as Mr. D. 

 Forbes had informed him were to be met with traversing Palaeozoic rocks in 

 Spain, Norway, and other countries. Taking all these facts into consideration, 

 he was inclined to hesitate for the present in accepting Mr. Jukes -Browne's 

 hypothesis. 



Mr. Forbes, with reference to Mr. Seeley's observations, stated that he had 

 found true eruptive lodes or dykes of phosphate of lime (phosphorite or apatite) 

 traversing the Silurian and Devonian strata and granites of Estremadura in Spain 

 and Portugal, and often extending for miles ; and also others breaking through the 

 metamorphic schists of the south of Norway. Some years back he had explained 

 the phosphorite in the deposits of Nassau as resulting from submarine eruptions, 

 which brought it up and left it on the sea-bottom in the form of breccia and tuff, 

 precisely as a volcanic rock would do under similar circumstances. So far as he 

 had examined the phosphatic nodules of the Cambridge Greensand, however, he 

 had not found that their mineral structure indicated any such eruptive origin. 



The Rev. T. G. Bonney remarked that Mr. Seeley's observations bore upon 

 a large question, affecting our whole system of geological nomenclature rather than 

 the immediate subject. The nomenclature being as it was, he thought Mr. 



