128 mr. j. mawson on the [May 1907, 



9. On the Cretaceous Formation of Bahia (Brazil), and on Verte- 

 brate Fossils collected therein. By Joseph Mawson, F.G.S., 

 and Arthur Smith Woodward, LL.D., F.R.S., F.L.S., F.G.S. 

 (Read January 9th, 1907.) 



[Plates VI-VIIL] 



I. Stratigraphy. [J. M.] 



At the end of the year 1859, Mr. Samuel Allport l communicated 

 to the Geological Society his discovery of a series of fossiliferous 

 Tocks, apparently of Mesozoic age, in the neighbourhood of Bahia 

 (Brazil). In 1870 the same formation was more adequately described 

 by Prof. C. F. Hartt, 2 who regarded it as probably equivalent 

 to the Neocomian of Europe ; and, in 1878, the whole of the 

 Cretaceous basin of Bahia formed the subject of a memoir by 

 Dr. Orville A. Derby. 3 The work of all these authors emphasized 

 the importance of systematic collecting from the highly-f ossiliferous 

 deposits of the series in question ; and it has been my pleasure 

 and privilege, at intervals during the past thirty years, to devote 

 considerable time to this task. Most of the fossil mollusca thus 

 obtained have been monographed by Dr. C. A. White, while the 

 fossil vertebrata have been described by the late Prof. E. D. Cope 

 and Dr. A. Smith Woodward. ~No summary of results, however, has 

 hitherto appeared; and, as my opportunities for continuing the 

 work are now almost at an end, I venture to offer to the Geological 

 Society some general observations, to precede a discussion of my 

 collection of vertebrate fossils, which has been prepared by Dr. Smith 

 Woodward. 



As already remarked by Allport, the Cretaceous rocks of Bahia 

 have a general north-westerly dip, but the series is so much 

 disturbed and contorted that the actual dip differs in almost every 

 section. It was, in fact, impossible for me to discover any regular 

 order of zones in the deposits, which are obviously an estuarine 

 series of lenticular beds of conglomerate, sandstone, and shale, 

 with occasional thin layers of shelly limestone. As noted by 

 Hartt and Derby, the conglomerates consist chiefly of stones which 

 may be of local origin, but the rounded pebbles of compact bluish 

 limestone appear to me to resemble a rock which I have not seen 

 nearer than Inhambupe (130 kilometres north of Bahia) or Almas 

 and Brejo Grande (270 to 320 kilom. west and south-west of Bahia). 

 In places (as, for example, at Itacaranha), pieces of wood in jet-like 



1 ' On the Discovery of some Fossil Remains near Bahia in South America 

 Quart. Journ. Geol. Soc. vol. xvi (1860) pp. 263-68 & pis. xiv-xvii (with notes 

 on the fish-remains by Sir Philip Egerton, on the mollusca by Prof. J. Morris, 

 and on the entomostraca by Prof. T. Rupert Jones). 



2 'Geology & Physical Geography of Brazil' Boston & London, 1870, 

 pp. 346-60, 555. 



3 ' A Bacia Cretacea da Bahia de Toclos os Santos' Archiv. Mus. Nac. Rio 

 de Janeiro, vol. iii (1878) pp. 135-58, with map (pi. xii). 



