1897.] Recent Literature. 319 
below the disc. No free head was observed in the latter genus, but it 
may be concealed. 
Dr. Alex. Gétte, the distinguished Professor of Leipzic, gives a de- 
tailed account of his researches on the embryology of the caudal verte- 
brae of certain existing Lacertilia, with the view of demonstrating 
that my doctrine that the intercentra of the caudal vertebre of the 
Reptilia are not the homologues of the intercentra of the dorsal series 
of other vertebrates, and that the conclusion that the vertebral bodies 
of the Anamnia are chiefly composed of intercentra, while those of the 
Amniota are centra, is incorrect. He commences by misunderstanding 
the (p. 876) ground of the doctrine he seeks to overthrow, a very com- 
mon cause of unnecessary polemic. He says: “ The alleged homology 
of all described intercentra depends exclusively on the assumption that 
the continuity of the chevron bones with the perichordal bone above 
them, indicates their genetic identity, so that the latter are an expan- 
sion of the bases of the former, or reversed, the chevron bones are pro- 
cesses of the perichordal bones. On the contrary, I can, on the basis 
of my observations on the development of the saurian vertebra, assert 
as a fact, that a genetic identity of the intercentra with their inferior 
arches does not exist, and that these parts originate rather as distinctly 
separate, as the superior arches and their vertebral bodies.” No con- 
tradiction of these facts can be justly derived from my papers on the 
subject, and if I have used the word “ continuity” in describing the 
relations of the chevron bones with the caudal intercentra, it has been 
in the sense of homological continuity, as in the case of the superior 
arches and the pleurocentra. That this is true is apparently proved 
by the facts of paleontology. The ground which is fundamental in 
this connection is the fact, that the elements which in the genus Crico- 
tus do support the chevron bones and do not, or only in part support 
the neural arches, and which may be identified by their contracted 
superior long diameter, are continued all the way through the sacral, 
dorsal and cervical regions from the caudal, so that the homology may 
be directly traced. And secondly, because in some species of Cricotus 
the upper part of the intercentrum in the dorsal region is so pinched 
as to reduce the body to the form, as it has the position of a large rep- 
tilian intercentrum. 
r. Gétte denies the homology of the caudal and dorsal intercentra 
and of different intercentra with each other on the following grounds. 
First, the centra of vertebrata are not homologous bodies; second, the 
chevron bones in Batrachia are primitively distinct from the caudal 
22 
