The Osteology of Dallia pectoralis. 353 
spur projeets upward from the prootie, nearly reaching the car- 
tilaginous area on top of head, between the pterotic and frontal, 
directly over it. 
There is no alisphenoid unless a descending wing from the 
frontal can be interpreted as an anchylosed one. This seems im- 
probable as in other forms the descending wing is nearly always 
present, the alisphenoid being articulated to it. On the other hand 
the prootie articulates to it as it does to the alisphenoid when 
present. 
The sphenotie offers no peculiarities. The parasphenoid is very 
broad and thin, anteriorly growing broader and less ossified. It 
sends no lateral wings up to the prooties. Posteriorly it ends 
squarely a short distance anterior to the oceipital condyle. 
The vomer is very small, but little larger than the patch of 
teeth it bears. It overlies the parasphenoid, barely extending 
anterior to it and not nearly reaching to its lateral edges. It is 
easily detached, coming off with the investing membrane of the 
mouth. 
The outline of the frontals together roughly form a diamond. 
From the projecting lateral angle of each a neural tunnel extends 
medially to about the middle of the bone, then turns sharply forward, 
opens at the anterior end of the bone, and is continued through 
the very small tubular nasals. On the frontals two pores open into 
it; one at its angle and one a short distance forward. 
On the rostrum projecting a little over the premaxillaries, are 
a pair of bones suturally joined to each other posteriorly, and 
diverging anteriorly. They are homologous with the bones of the 
pickerel numbered 2 by Huxrey in his Anatomy of Vertebrate 
Animals, which with his bone number 1 (homologous with the nasals 
of the Acanthopteri) are said by that author to be bones replacing 
nasals. Aucıs!) identifies them with the dermal ethmoid of Salmo 
and Amia. which, however, are not homologous with the more deep 
seated ethmoid of the Acanthopteri. They overlie the large ethmoidal 
cartilage, which projecting laterally bears a small ossification, the 
prefontal. The olfactory nerve pierces the ethmoidal cartilage at 
some distance from the prefrontal. 
1) Aurıs, E. P. jr., On the morphology of certain of the bones of the 
cheek and snout of Amia calva, in: Journ. Morphol., V. 14, No. 3, 1898, 
p. 434. 
