ON THE MORPHOLOGY: OF RIGS AND THE FATE 
OF THE ACTINOSTS On tHE jie DEAN 
FINS IN: FISHES. 
Dr. G. BAUR, 
New Haven, Conn. 
In a paper read before the American Association for the 
Advancement of Science, two years ago, I reached the follow- 
ing conclusions on the ribs of vertebrata :'— 
“1, The ribs are developed detween the myocomata ; they are 
therefore zxtervertebral. 
2. The ribs are originally one-headed and connected with 
well-developed intercentra. 
3. All forms and connections of the other ribs can be derived 
from that condition. 
4. The lower arches of the caudal vertebre are either formed 
by true ribs, the oldest fishes (Ganoidei, Dipnoi), or by processes 
of the intercentra (Teleostei, Stapedifera). 
5. The connection between the Dipnoans and the Stapedifera 
is still missing. 
6. Some remarks on the nomenclature of the elements of 
the vertebral column. 
Owen’s names, ‘neurapophysis’ and ‘pleurapophysis,’ are 
not correct ; the neural and pleural arches are no processes of 
the vertebrz, but are distinct parts. 
The two elements composing the neural arch ought to be 
called the zeuvoids; the two elements composing the pleural 
arch, the pleurozds. 
The spines connected with the neuroids ought to be called, 
as before, zeural spines; those connected with the pleuroids, 
pleural spines. 
The real centrum of the vertebra ought to be called centrum ; 
the lateral elements composing it, hemzcentra (Albrecht), not 
pleurocentra. 
The name intercentrum ought to be preserved.” 
1 Baur, G. On the Morphology of Ribs. American Naturalist, October, 1887, p. 45. 
