No. i.] INTERCALATION OF I'ERTEBRAE. 49 



In all these cases we have shifting of the pelvis. 



Professor Bumpus does not believe in intercalation, but there 

 are true cases of intercalation, as I shall show. The Gavial 

 case has been accepted by Parker, but not by Bumpus. The 

 original description was published in 1886 ('86, p. 689, also 

 >91 P- 334)- " Bei einem Exemplar von Gavialis gangcticns 

 fincle ich 25 praesacrale Wirbel ; zwischen dem 9. und 10. Wirbel 

 ist ein solcher eingeschaltet, wie aus der Configuration der Dia- 

 und Parapophysen genau bestimmt werclen kann." It is a well- 

 known fact that in all living Crocodilia with normal vertebral 

 column there are 24 presacral vertebrae, two sacrals, and many 

 caudals. All the presacral vertebrae are concave-convex; the 

 first sacral is concave in front, plane behind; the second plane 

 in front, concave behind; the first caudal is biconvex. In the 

 Gavial with 24 presacrals and the Gavial with 25 presacrals, 

 the two sacrals and the first caudal are absolutely identical in 

 structure. In the first case the first caudal is the 2/th, in the 

 second the 28th. Therefore one vertebra must have been inter- 

 calated between two of the 24 presacral vertebrae. I determined 

 these vertebrae as the 9th and loth. Here are my reasons. It 

 is very well known that the vertebrae of the Crocodilia are very 

 different in form, passing from the atlas to the sacrum, and 

 these differences have been very well described by Huxley in 

 his Anatomy of Vertebrates (1871). Omitting a consideration 

 of the first two vertebrae, the atlas and axis, concerning the 

 identity of which there can be no doubt in the two specimens, 

 we may examine the following vertebrae. The other cervicals 

 all possess ribs with distinct and long capitula and tubercula 

 -the latter attached above the neurocentral suture to the 

 neural arch, the former to the centrum below the neurocentral 

 suture. The body of each cervical rib, after the second and as 

 far as the seventh and eighth, is short and prolonged in front 

 of, as well as behind, the junction of the capitulum with 

 the tuberculum; and the several ribs lie nearly parallel with 

 the vertebral column and overlap one another. The ribs of the 

 eighth vertebra are a little longer than those of the seventh ; 

 the ninth rib is very much longer than the eighth, and has a 

 terminal cartilage. 



