PE0F. T. H. HUXLEY ON STAGONOLEPIS ROBERTSONI. 423 



27. On Staoonolepis Robertsoni, and on the Evolution of the 

 Crocodilia. By Prof. Thomas H. Huxley, LL.D., Sec. U.S., 

 E.G.S, (Read April 28, 1875.) 



[Plate XIX.] 



Nearly seventeen years ago I had the honour of laying before the 

 Geological Society * an account of such remains of a remarkable 

 reptile (Stagonolepis Robertsoni) as, up to that time, had been found 

 in the sandstones of the neighbourhood of Elgin, and the conclu- 

 sion at which I had arrived, " that Stagonolepis is, in the main, a 

 Crocodilian reptile." 



These remains, however, like all the other fossils from the same 

 district which have come under my notice, were not in a condition 

 very favourable to their interpretation. "With the exception of a 

 few dermal scutes, I do not think that a single entire bone, or cast 

 of a bone, has come into my hands; and the most instructive 

 specimens have not been the bones themselves, the osseous matter 

 being always soft, friable, and injured, but their casts in the sand- 

 stone. The evidence afforded by the remains of vertebras and scutes 

 was sufficiently decisive to warrant my conclusion as to the general 

 nature of the animal; but, in respect of the other parts of the 

 skeleton, the surmises which I made in 1858 needed confirmation, 

 or the reverse, by the study of additional materials. 



Such materials have from time to time been obtained by the ex- 

 ertions of my friend the Rev. Dr. Gordon, of Birnie, near Elgin, 

 who, aided by a grant from the Donation Eund of the Royal Society, 

 has undertaken the exploration of the fossiliferous beds whenever 

 the operations of the quarrymen laid them bare, and has from time 

 to time sent me consignments of valuable and instructive specimens. 

 Erom these and others, for which I am indebted to Mr. Grant of 

 Lossiemouth, I have been enabled to make numerous important addi- 

 tions to my knowledge of Stagonolepis ; so that at present I am ac- 

 quainted with the following parts of its skeleton : — 



1. The dermal scutes, which formed a dorsal and a ventral 



armour. 



2. Yertebrse of the cervical, thoracic, lumbar, sacral, and caudal 



regions. 



3. Ribs. 



4. Parts of the skull and teeth. 



5. The scapula, the coracoid and the interclavicle. 



6. The humerus and (probably) the radius. 



7. The ilium, ischium, and pubis. 



8. The femur and (probably) the tibia. 



9. Two metacarpal or metatarsal bones. 



* "On the Stagonolepis Bobertsoni (Agassiz) of the Elgin Sandstones." 

 — Quart. Journ. Geol. Soc. 1859 



