1897.] Recent Iiterature. 321 
As regards the precedence of the rhachitomous over the embolome- 
rous type of vertebral column, tologic evi trates that 
this was the history as regards Teleostomous fishes and Digitata (or 
Amniota), as Zittel has shown to have been the case in the former and I 
have shown as to the latter. Embolomerous forms do not come first in 
geologic time in these divisions, but later. I have not made any attempt 
to interpret with respect to this hypothesis, the structure of the verte- 
bral column in the Selachii. They afford, however, no support to Prof. 
Götte’s hypothesis, since it is probable that the Selachian vertebral col- 
umn originated in a rhachitomous condition. In notochordal sharks, 
e. g., the Ichthyotomi, the primitive vertebre are represented by centra 
above and intercentra below, as in the Teleostomi and Stegocephali, 
The superior segment supports the neural arch, and the inferior 
the hemal arch. Götte’s first proposition, that the embolomerous 
condition is the primitive one, is shown to be untrue as to the true 
fishes by the facts adduced by Zittel and others, since the primitive 
vertebree of fishes described by these authors is rhachitomous and not 
embolomerous. Prof. Gétte does not observe that his fig. 6 (text, p. 
384) of Callopterus, represent rhachitomous caudal vertebrz, and dor- 
sal vertebre in which the centrum (pleurdcentrum) is greatly re- 
duced, so that the intercentrum becomes by far the larger part of the 
vertebral body. Thisis in exact accord with what is found in the Ste- 
gocephali, and is contributive evidence that the vertebral body in the 
Anamnia is intercentrum. That the body in the Amniota is centrum is 
abundantly proven by the characters of the Permian Pelycosauria. 
In this study we have again an excellent illustration of the relative 
value of embryologic and paleontologic research in determining the 
homologies of parts and phylogenies of types. As to this Prof. Goette 
expresses himself thus (p. 377): “Since these relations can only be 
directly observed or completely known in living animals, and not in 
the fossil Stegocephali, so it is a self evident proposition that the un- 
known can only be explained by the known, the extinet by the living 
animals.” This proposition must now, in view of the results of modern 
research be reversed so as to read as follows: Since these relations can 
only be completely known or directly observed in fossil animals, and not 
in the embryonic history of living forms, it is a self evident proposition 
that the unknown can only be explained by the known, the living by the 
extinct animals. Conceding the great value of embryology in the pre- 
mises, it has now become fully evident that it can only be understood 
when interpreted by paleontology. An excellent illustration is the 
case of the embryology of the vertebre of Amia, described by Hay and 
