ON PROTEROSAURUS SPENERI. 233 



the English Marl-slate was contemporaneous with, or deposited 

 about the same geological period as, the German Kupferschiefer. 



For the history and description of more complete specimens 

 we must refer to the classical monograph of Hermann von Meyer, 

 " Fauna der Vorwelt — Saurier aus dem Kupferschiefer der Zech- 

 stein-formation." 



The geological position in which these reptiles were found has 

 already been described in a former communication, so that it is 

 unnecessary to repeat it here, further than to state that they 

 were associated in the Marl-slate proper on the same stratigra- 

 phical horizon with such fishes as Platysomus, Palceoniscus, etc. 



The two specimens which we are about to describe were much 

 obscured in the matrix ; but by the skilful aid of Mr. Thomas 

 Atthey the whole of the bones have been perfectly developed at 

 the expense of much labour and judgment. One is the remains 

 of a well-developed individual ; but little more than vertebra 

 and a few of the ribs in a more or less dilapidated state are pre- 

 served ; but on another slab three or four perfect ribs have oc- 

 curred. The other specimen is in a much more perfect condition, 

 the principal bones of three of the limbs being well displayed, as 

 well as one of the fore feet and most of the ribs, which lie in re- 

 gular order on either side of the vertebral column. The former, 

 as already mentioned, is undoubtedly the remains of Proterosau : 

 rus Speneri, and the latter a new species of the same genus, Pro- 

 terosaurus Huxleyi. 



Proterosaurtjs Speneri, v. Meyer. (PI. VII.) 



The bones of the specimen of this species are in a very perfect 

 condition, the surface of them being quite intact, and in places 

 having even a semigloss. The vertebrae are lying articulated in 

 a much curved line, the animal having apparently died with the 

 spine arched violently backwards, as seems to have been the case 

 with all the examples hitherto obtained. In our specimen the 

 curve is even more sharp than usual, the remains of the column 

 forming almost half a circle. The anterior portion of it is thrown 

 suddenly back, and at the pelvic region it is as suddenly bent 

 upwards. 



