288 Structure of the Fossil Saurians. 



in the Gavial, and the differences between the single bones of 

 the head are in both animals far more considerable than be- 

 tween the two living species of Gavials. The teeth stand, as 

 in the crocodile in distinct alveoli ; but in the under jaw they 

 are alternately longer and shorter, which is not the case in the 

 Gavials. The longer tooth is usually twice as long as the 

 shorter. The teeth of the upper jaw appear to be of equal 

 size. On each side are first two small teeth, followed by one 

 very much larger, the largest of the whole. In the living 

 Gavial, we find on each side, first, a small tooth ; at a little dis- 

 tance another small one ; while again at some distance follows 

 a larger, and afterwards one somewhat larger still: the rest 

 being nearly similar to each other, and as long as the lower 

 teeth. The teeth of the fossil animal appear to be more 

 pointed and more strongly bent, and to have stood out more 

 prominently than in the Gavial ; and, besides, they are finely 

 striated lengthwise. The posterior surface of the vertebrae is in 

 the Aeolodon, somewhat concave, which has not yet been found 

 in any living Saiirus, but is only remarked in the Cetacea, 

 Batrachians, and Fish. The number of vertebrae in the fossil 

 animal is 79 ; in the Gavial, never more than 68. This dif- 

 ference consists in the tail of the former animal, which con- 

 tains 10 vertebrae more; which, however, in consequence of 

 their shorter, and therefore stouter, form, strengthen the 

 tail, but do not lengthen it with relation to the body. The 

 heads of the bones of the arm and leg, and of the phalanges, 

 appear to be formed more roughly, to terminate more strait, 

 and appear more similar to those of the Cetacea, than of the 

 living Saurians, in which the elevations and depressions of 

 the heads of the bones approximate more nearly to those of 

 the land Mammalia. The number of the fingers and toes 

 accords with those of the Crocodiles. The relation of the 

 long bones is, however, different. The length of the femur 

 amounts to somewhat more than double the length of the 

 tibia, which is the case in none of the living Crocodiles: in 

 the Gavial this length only amounts to a quarter more. 

 The tibia, also, is comparatively larger than in the Gavial. 

 The pelvis differs widely from the Crocodile and La- 

 certa, and excludes the fossil animal from any association 

 with these. Along with the fossil skeleton there were also 

 on the same bed of stone, scales which must have belonged 

 to this animal, so that its skin appears to have consisted of 

 actual scales. This fossil Saurus, whose type cannot be classed 

 with any genus or subgenus of the division of the living Cro- 

 codiles or Lacertae, I have, from the alternating size of its 

 teeth, named the Aeolodon. It is the Gavial de Monheim of 



