THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE IV. VOL. IV. 



No. IV.— APEIL, 1897. 



(DIRXO-XIST J^Xj JLI^TIGILES. 



I. — • On a New Specimen of the Mesosaukian Eeptile, 



Stereo&ternum tumidum, from San Paulo, Brazil. 



By Arthur Smith Woodwaud, F.L.S., F.G.S., 



Of tlie British Museum (Natural History). 



(PLATE V.) 



"HElS" in Eio de Janeiro last October, Dr. Orville A. Derby 

 gave me for publication in tbe Geological Magazine the 

 photograpli of a fine new specimen of Stereostermim tumidum, 

 reproduced in the accompanying Plate V. Like the type-specimens 

 discovered by Dr. Derby, it was obtained from a light-grey, 

 limestone in a quarry on the estate of Senhor Antonio Machado, 

 de Campos, near the town of Limeira, in the State of San Paulo,, 

 Brazil. It is intei'esting as showing for the first time the general 

 proportions of the trunk and tail of this strange extinct reptile ;. 

 and it also permits the identification of another fossil from the same 

 formation, now ia the British Museum, which has hitherto escaped 

 notice. 



Stereostermim was originally described by Professor Cope in 1886 ^ 

 from an imperfect trunk and other fragments, which he could not 

 assign to a detinite systematic position, but believed to represent an 

 aquatic reptile veiy similar to the small Mesosaurus from the Karoo. 

 Formation in South Africa. A year later he received from 

 Dr. Derby a " nearly entire specimen," showing the head, neck, and 

 fore-limbs, and this was the subject of a brief note in the " American 

 Naturalist." ^ Professor Cope remarked : — " The neck is moderately 

 elongate, and includes nine vertebree besides the atlas. The 

 vertebrEe have robust transverse processes and slender cervical ribs. 

 The skull is elongate and acuminate, and its bones are apparently 

 fragile. Little of its structure can. be made out. The teeth are 

 slender, acute, and nearly straight, and are planted in (?) shallow 

 alveoli." About the same time Dr. Baur^ emphasized the 



^ E. D. Cope, "A Contribution to the Vertebrate Palaeontology of Brazil": 

 Proc. Amer. Phil. Soc., vol. xxiii (1886), p. 7, pi. i. 



^ E. D. Cope, " The Carboniferous Genus Stereosternuni " : Amer. Nat., vol. xxi 

 (1887), p. 1109. 



^ G. Baur, Zool. Auzeiger, 1886, p. 189, and " On the Phylogenetic Arrange- 

 ment of the Sauropsida," Journ. Morphology, vol. i (1887), p. 103. 



DECADE IV. VOL. IV. NO. IV. 10 



