664 
lies in the canal enclosed between the body of the vertebra mesially, 
and the rib-carrier and its dorsal process below and above. 
The condition of single-headed ribs is attained here, as in Spe- 
lerpes, by the coalescence with the rib-carrier, of its dorsal process 
in the last two or three trunk segments. 
The sacral vertebra, however, again possesses a bicipital rib, and 
in the specimen of which I have made sections, a minute blood-vessel 
pierces the base of the rib-carrier. In the absence of observations 
on young specimens it is impossible to assign any great importance 
to its occurrence; but it may serve to indicate caution in estimating 
the significance of the similar, much larger, foramen in the base of 
the transverse processes of the anterior caudal vertebre. 
Ill. Desmognathus fusca. 
In Desmognathus the dorsal and ventral roots of the spinal nerves 
leave the osseous canal by separate foramina distinct from the inter- 
vertebral foramen. 
The rib- apparatus is characterised by its great slenderness and 
the greater independence of the rib-carrier and the homologue of its 
dorsal process. 
Basal processes are present and show a gradual shifting of their 
point of union with the vertebral body as we proceed backwards: at 
first quite ventral, then lateral, and finally reaching as high as the 
junction of the neural arch !). 
IV. Conclusion. 
The dorsal buttress of the rib is really attached to the trans- 
verse process, not to the neural arch. Its mode of attachment is iden- 
tical with that existing between the rib-carrier and the rib. Never- 
theless, I cannot regard it as indicating the double nature of the ribs 
and transverse processes, rather as merely a modification to limit the 
movements in the vertical plane, of an originally single rib. 
However the study of larve and young specimens of Plethodon 
and Desmognathus would very probably give more satisfactory data. 
Freiburg i. B., 30. July 1897. 
1) Cf. Gaprrrt, Amphibien-Rippen, |. c. in reference to the ribs of 
Anura, 
Abgeschlossen am 31. August 1897. 
MEZ” Dieser Nummer liegen Titel und Inhaltsverzeichnis zum 
XIII. Bande bei. 
Frommannsche Buchdruckerei (Hermann Pohle) in Jena. 
