ROOM III. GEOSAURUS MACROSPONDYLUS. 175 



apertures terminate in two distinct orifices, instead of being 

 blended into a single opening as in the recent Gavials ; and 

 the Steneosaurus, in which the breathing canals end in two 

 nearly semicircular vertical orifices at the extremity of the 

 muzzle. 1 



Geosaurus (G. Scemmeringii). Wall-case A B. (See ante, 

 p. 153.) The remains of a small crocodilian reptile, con- 

 sisting of a considerable portion of the vertebral column 

 with the ribs, and the anterior part of the skull with the jaws 

 and teeth, are deposited on the lowermost ledge in the angle 

 between the Wall-cases A and B. These fossils are men- 

 tioned in the official " Synopsis of the British Museum," as 

 the head and other parts of the Geosaurus, (Lacerta gigantea, 

 of Scemmering,) found in the white Lias, at Monheim, in 

 Franconia ; being the original specimens figured and described 

 by Soemmering, in the Transactions of the Academy of 

 Munich. They are also figured and described by M. Cuvier, 

 (" Oss. Foss." tome v. p. 338, PI. XXI. figs. 28.) 



The vertebral column, in two portions, partially imbedded 

 in fissile marlstone, is placed in the long cases in the centre ; 

 and the two parts of the cranium and jaws are in the small 

 cases on the right hand. 



The teeth of this extinct crocodilian reptile are flat, 

 pointed, and recurved backwards like a sabre, the edges being 

 finely serrated ; there are seventeen on each side the upper 

 jaw. The eye was very large, and the sclerotic coat protected 

 by a zone of osseous plates, as in the Ichthyosaurus. The 

 vertebrae are biconcave and slightly contracted in the middle } 

 their transverse processes are very large and strong. 



From the form and structure of the cranium, M. Cuvier 

 inferred that the original held an intermediate place between 

 the crocodiles and monitors, but was most nearly allied to 

 the latter. The length of the reptile was probably nine or 

 ten feet. 



Macrospondylus. Wall-case B. Uppermost Shelf. The 



1 " In the Teleosaurus the nostrils form almost a vertical section of the 

 anterior extremity of the beak ; in the Steneosaurus this anterior termi- 

 nation of the nasal canal had nearly the same arrangement as in the 

 Gavial, opening upwards, and being almost semicircular on each side." 

 Dr.BucklancTs " Bridge-water Essay " p. 252, PI. XXV. 



