SCHLEGEL S GAVIAL. 5 



genera with regai'd to the shape of the second rib and its 

 attachment to the vertebrae. I am not able to confirm his state- 

 ments regarding Gavialis and Alligator. In the case of the 

 latter, the more forward position assigned by him to the costal 

 capitulum may be due to individual variation, but I cannot 

 help thinking the author is mistaken in attributing a rudi- 

 mentary diapophysis to the neural arch of Gavialis. In the 

 specimens I have examined two very distinct processes are 

 present on the axis centrum, and I have satisfied myself on a 

 specimen in spirit that the ligamentous capitulum is attached 

 to the upper of these processes, which is widely separated from 

 the supposed diapophysis figured by Dr. Baur. 



I have examined the atlas and axis in Gavialis gangetieus, 

 Tomistoma schlegeli, Crocodili niloticns, americamis and porosua, 

 Osteolsemus tetraspis, Alligator misoissippiensis. Caiman sclerops 

 and C. latirostris, and find important differences which are de- 

 serving of notice. 



In Alligator the first rib is attached to the lower surface of 

 the hypapophysis and in contact with, or narrowly separated 

 from, its fellow at the base; the second rib, in the adult, is 

 deeply forked, and attached by its cajiitulum to the centrum of 

 the atlas, by its tuberculum, to the anterior part of the centrum 

 of the axis, which, however, does not develop any tubercle or 

 transverse process. In a new born specimen I find both capit- 

 ulum and tuberculum inserted on the axis, shewing the rib to 

 shift forward with age, a further confirmation of the view that 

 this rib, usually attached to the first vertebra, really pertains to 

 the second. 



In Caiman the first rib is as in the preceding, but the 

 second, deeply forked, is entirely on the centrum of the atlas, 

 without the latter bearing processes for its attachment. 



In Crocodilns the first rib is more on the side of the 

 hypapophysis, and widely separated from its fellow ; the second 

 is but feebly notched in its proximal portion, and the somewhat 

 ill defined capitiilum and tuberculum join two strong knob-like 

 processes on the centrum of the atlas. 



In Gavialis Ihe first rib conforms to the preceding type, but 

 the second is deeply bifm-cate, the tuberculum ligamentous, and 

 attached to two processes on the centrum of the atlas. 



Tomistoma has been noticed above. Osteoloemus curiously 

 agrees with it. 



