192 EDWARD PHELPS ALLIS, JR. 
Lundborg, there is a considerable distance between the hypo- 
physial invagination and the oral plate, and as the mandibular 
branchial bars certainly lie morphologically posterior to the oral 
plate, it would seem as if the primary upper lip must lie between 
the plate and the hypophysis. 
The conditions in the embryos above referred to thus give 
conflicting evidence as to the relations, in the Plagiostomi and 
Teleostei, of the primary and secondary upper lips to the hypoph- 
ysis, but in embryos of Amia and Acipenser positive evidence 
is given of these relations, in these fishes, by Reighard and Mast, 
and von Kupffer, respectively. In Amia, Reighard and Mast 
(08) say that the adhesive organ is developed from entoblastic 
tissues which probably represent the anterior head cavities of 
the fish, and that this organ only secondarily acquires connection . 
with the ectoblast. This ectoblastic connection, when acquired, 
lies between the fundament of the hypophysis and the stomo- 
daeum, and the adhesive disk of larvae is developed there; and 
as my figures of these larvae of Amia (Allis, ’89) show that the 
lips of this fish, both primary and secondary, lie oral to the 
adhesive disk, they must both necessarily develop from tissues 
oral to the hypophysis. In Acipenser, also, the adhesive organ 
lies between the hypophysis and the stomodaeum (von Kupffer, 
93), and as the adhesive organ of embryos is said to become the 
barbels of the adult (Reighard and Phelps, ’08), and as the 
upper lip of the adult lies oral to these barbels, this lip of this 
fish, whether it be simply a primary one or a primary and 
secondary combined, must also lie oral to the hypophysis. 
It thus seems certain that the secondary upper lip, at least, 
varies, in different fishes, in its relations to the fundament of the 
hypophysis, lying oral to it in the Ganoidei and aboral to it in 
Salmo; and this difference in position is associated with the 
presence or absence, in embryos of these fishes, of an adhesive 
organ. The fold of the secondary upper lip must accordingly 
be developed later than either the hypophysis or the adhesive 
organ, and, as it pushes forward from the angle of the gape, it 
passes oral or aboral to the hypophysis accordingly as that organ 
is more or less remote from the oral plate. Keibel’s statement 
