64 THE AMERICAN NATURALIST. (Vor. XXXIX. 
(Fig. 6), and his identifications are adopted by Howes and 
Swinnerton. Yet it seems probable that here again the dermar- 
ticulare (da) has been termed the angulare and the angulare (az) 
the splenial. Judging by Günther's figures, which do not agree 
with that of Baur, it is possible that the angulare is an angulo- 
splenial as he suggests, but the observations of Howes and 
Swinnerton show no separate elements. The articulare cannot 
be a compound structure like that in the Lacertilia, for, in the 
development no dermarticulare, other than that interpreted às 
such here, occurs. 
In the case of the alligator (Fig. 7) I feel less certain. As 
is well known, besides the articulare (a), three bones form the 
inner surface of the jaw, a bit of the dentary (7) being visible 
near the tip. There can be no question about the coronary (c) 
while the large plate extending forward from the coronoid (s) is 
as Clearly the splenial, if the conclusions regarding the other 
forms studied be correct. The remaining element (an) is the 
more problematical. Baur calls it the splenial and thinks that 
the angulare is fused with the articulare. It is clearly not the 
splenial, but it exhibits characteristics of both angulare and 
dermarticulare, being like the dermarticulare in its articulation 
with the coronoid, but like the angulare in the rest of its extent. 
There is no separate bone on the inner side of the articulare and 
there is a large gap in front of the articulare, extending to the 
coronoid, which in all other forms is occupied by the dermarticu- 
lare. Hence until a study of the development shows that this 
conclusion is untenable I prefer to call it the angulare and to 
assume that the dermarticulare has failed to develop. It is the 
angulare of Cuvier. 
These comparisons need to be continued into the Ichthyopsida 
and especially into the Stegocephala and the ganoids where con- 
siderable confusion exists. 
