4 SCHLEGEL S GAVIAL, 



Metriorhynchus (P.Z.S. 1888, p. 419) the presence on the 

 " lateral pieces " {neurapophysis) of the atlas of the tubercle 

 situated in the level of the diapophysis on the epistropheus, and 

 he concludes that this tubercle should rank as an upper atlantal 

 transverse process or diapophysis. I have been able to verify 

 the correctness of this statement on several well preserved 

 atlases of Metriorhynchus still undescribed, from the Leeds 

 Collection, which my colleague, Mr. Andrews, has kindly shewn 

 me in the Geological Department of the Bi'itish Museum ; and I 

 quite agree with Hulke that " the position of this little process 

 in serial line with the upper transverse process of the other 

 cervical vertebrae speaks distinctly in favour of its diapophysial 

 character." We are, in consequence, justified in assuming that 

 although, as we know from one specimen, the first rib is not 

 forked, it must have been connected with the diapophysis by 

 ligament, its head being attached to the side of the hyjjapophysis 

 ( " basilar piece " ) of the atlas, or rather between the latter and 

 the centrum (odontoid bone) ; and such a condition may be 

 regarded as the most primitive known among Crocodilians, and 

 as one from which, as Hvilke has shewn, the abnormal position 

 of the first rib of recent forms may be derived and explained. 



The second rib in Metriorhynclms was attached by its 

 capitulum to the anterior border of the lower surface of the 

 centrum of the axis, or between the latter and the centrum of 

 the atlas, and by its tubercu^lum to a process (diapophysis) of 

 the neurapophysis of the axis. 



As regards recent Crocodilians the information to be derived 

 from books appears contradictory, principally from the fact that 

 the various authors have dealt with different genei'a, and have 

 in some cases generalised their observations to the whole group. 



Cuvier (Ossem. Foss.) describes and figures the second rib 

 in Orocodilus j^orosus as single - headed and attached to the 

 odontoid bone. Owen (Osteol. Cat. Mus. Coll. Surg.) ascribes 

 to the same rib, in Gavialis gangeticus, a forked head attached 

 to two transverse processes of the odontoid bone. According to 

 Stannius (Zoot. Amph., p. 26) the rib is forked, and the two 

 branches are attached on the limit between the odontoid bone 

 and the centrum of the axis. Briihl (Skel. Crocod.) figures, in 

 Caiman palelhrosus, the rib as forked, with capitulum and tuber- 

 culum on the odontoid bone, near its suture with the axis. In 

 Huxley's " Anatomy of Vertebrated Animals " it is described in 

 crocodilians generally as attached to the os odontoideum and 

 to the second centrum by distinct capitvilar and tubercular 

 processes. Baur (Amer. Nat. 1886, p. 228) was the first in 

 attempting to shew what, if any, differences exist between the 



