1892.] The Head of an Embryo Amphiuma. 679 
ence of a turbinal, the absence of a parasphenoid and the 
presence of a basisphenoid are all points of importance, as is 
also the frequent presence of two rows of teeth. Again, in the 
Cecilians we find a multiplicity of bones such as occurs in the 
lower Ichthyopsida but not in the Urodeles, and which conse- 
quently cannot be derived from the latter. Regarding the 
chondrocranium of the Gymnophiona no comparison can be 
made until the appearance of the promised paper by Burck- 
hardt. 
The view is quite common that the origin of the Batrachia 
(sens. lat.) must be sought in the Dipnoi. Thus Cope says 
(Am. Nart., xviii, p. 725-6, 1884): “The Batrachia have origi- 
nated from the sub-class of fishes, the Dipnoi, though not from 
any known form.” 
This view had doubtless its foundation in the existence of 
both gills and lungs in these forms. As yet, however, no care- 
ful study of the distribution of the cranial nerves and of the 
ontogeny of the chondrocranium of any Dipnoan has been 
published, and until we have more detailed accounts than 
have as yet been made it is safe to assume that the resem- 
blances which have been pointed out between the Dipnoi and 
the Urodeles are those derived from a common ancestry. Of 
these resemblances probably the most important is that of the 
relation of the mandibular arch to the skull. Thus Huxley 
has divided the Ichthyopsida into autostylic, hypostylic and 
amphistylic groups, and has shown the close resemblances of 
the Amphibia to the Dipnoi, Chimeroids and Marsipobranchs 
in the ampistylic character of this connection of the quadrate 
with the cranium. It is, however, to be noticed that in the 
Urodeles the pterygoid cartilage never has that close relation 
to the cranium that this thesis demands, while the autostylic 
condition arises comparatively late in development, and never 
attains that completeness which a Dipnoan ancestry would 
imply. ; 
In short, I would prefer to trace the origin of both Dipnoi 
and Urodeles from a crossopterygian ganoid ancestry, the 
former being the apex of their line of development, the latter 
tracing their descent through the Stegocephali. 
