` 
944 General Notes. 
gosaurus articulate in the anterior region of the vertebre 
the ribs, as seen in Amia, are still preserved in the Pem 
in which the capitulum was still ossified, but was already 
ported from the rudimentary intercentrum to the centr 
_ This translocation has gone still further, in a way that 
downwards, forming a groove on the posterior part of the 
of the intercentrum. Therefore the single-headed ribs of 
both the intercentrum and neurapophysis, in the posterior re 
with the neurapophysis only. 
In the living Batrachia the double-headed ribs are-articul: 
proper or the intercentrum, as Professor Cope is inclined W 
believe, cannot yet be determined. Sphenosaurus certainly is ak 
a connecting form, but a true reptile, as I have proved. 
The Ribs of the Amniota.—Signs of the original condition & 
E 
Pelycosauria, the Sphenodontidæ, and the Mammalia. 
In the Pelycosauria the ribs are connected with the 
developed intercentra; there would be no difference from Ams 
if the ribs were not two-headed. A second head is develope 
Sphenodon is the same as in the Pelycosauria, but the tube 
rudimentary or disappeared entirely. orf 
he one-headed ribs of the Lacertilia, Pythono pi T 
Ophidia, have originated from the condition seen in Spheao’" 
The capitulum has gone entirely. ilia, Di 
The two-headed ribs of the Ichthyosauria, Crocodillay 
sauria, Ornithosauria, have developed from a form like Sph . 
um p 
mediate vertebrz. 
The results of the present: paper are: 
