424 PEOF. T. H. HUXLEY ON STAGONOLEPIS EOBEETSONI, 



Under these circumstances, it is possible to form a distinct and 

 tolerably complete conception of the nature of Stagonolepis, and to 

 compare it with other reptiles, so as to arrive at a just notion of its 

 affinities. 



So far as the vertebrae, ribs, scapula, and dermal armour are con- 

 cerned, I have nothing to alter in the views which I took of the 

 nature of the bones and their systematic significance in 1858. The 

 bone which, in the body of my paper, I interpreted as a coracoid, 

 turns out to have been correctly identified ; while that referred to 

 in the note at p. 459, and which led me to doubt whether I was 

 right in this interpretation, has been shown by better specimens 

 to have been an ilium seen from the inner side. The distal moiety 

 of a limb-bone, which is regarded as a femur at p. 452, is shown, 

 by further evidence, to be a humerus ; and, finally, the mandible with 

 long curved teeth, which I supposed might belong to Stagonolepis, 

 certainly appertains to some other animal. 



It is a very remarkable circumstance that, up to the present date, 

 the fossiliferous sandstones of Elgin have yielded remains of Stago- 

 nolepis (several individuals, some of which must have attained a 

 length of 12 or 14 feet), of Ilyperodapedon (one almost complete 

 specimen, half another, and fragments of others, the largest pro- 

 bably 6 feet long), of Telerpeton (two nearly entire specimens about 

 a foot long), and of the large animal to which the mandible with 

 long curved teeth belonged, and absolutely nothing else. Not a 

 trace of other vertebrate or invertebrate animals, or of plants, has yet 

 been detected ; and the only other indication of life is the well-known 

 series of foot-prints, which, so far as I can ascertain, do not occur in 

 the same beds with the reptilian remains. As Stagonolepis, at any 

 rate, was a carnivorous animal, and must have needed a consider- 

 able supply of aliment, the absence of any trace of the animals on 

 which it fed (unless, as is not very likely, it devoured Lizards) is a 

 curious illustration of the value of negative evidence. 



Prom the evidence which has now been collected, and which con- 

 sists entirely of specimens associated with the characteristic scutes of 

 fttagonolepis, it is demonstrable that, in outward form, this reptile 

 must have resembled one of the Caimans or Jacares of the present 

 fauna of intertropical America, that it possessed strong limbs, of 

 which the anterior were at least as large, in proportion to the pos- 

 terior, as in the modern Orocodilia, but that Stagonolepis differed 

 from the Caimans in possessing a long and narrow skull, more like 

 that of a Gavial. 



As in the existing Caimans and Jacares, the trunk and tail were 

 protected by a strong armour, composed of a dorsal and a ventral set 

 of thick bony dermal scutes, which, in the trunk, were so arranged 

 as to constitute separate dorsal and ventral shields, while in the tail 

 they formed a continuous girdle. 'In contradistinction to existing 

 Orocodilia, the dorsal shield was made up of not more than two 

 longitudinal series of scutes, and the ventral shield of not more 

 than eight series in any part. 



