MAXILLARY AND VOMER BONES OF POLYPTERUS 383 
To control this statement I have now endeavored to trace the 
labial folds and furrows in the Amniota, and for this purpose I 
have used exclusively Fuchs’s (’07, ’08) very careful descriptions 
of the development of the primary and secondary palates in 
these animals. 
In all of the Amniota the crest of the secondary upper lip passes 
either between the nasal apertures of either side or across the 
oral nasal aperture, the fold thus either simply traversing the 
nasal bridge, without overlapping its oral edge, or slightly 
overlapping that edge and so adding somewhat to the width of 
the bridge (Allis, 718). The lateral portions of the secondary 
upper lip are formed by the so-called maxillary processes of 
embryos, and Fuchs says (’08, p. 221) that those processes take 
part in the formation of the primary palate in mammals, but 
not in the Sauropsida. In early embryos of Emys he, in his 
figures, shows the process running forward along the lateral 
edge of the oral (internal) nasal aperture and then forward along 
the external surface of the lateral nasal process nearly to the 
oral end of the aboral (external) nasal aperture. The ridge of 
the process is bounded on either side by a furrow, and another 
furrow overlies the line of fusion of the nasal processes above 
the nasal groove. This latter furrow is joined, somewhat 
anterior to the oral nasal aperture, by the furrow that bounds 
mesially the maxillary process, and Fuchs considers this fusion 
of ‘these two furrows to mark the oral end of the nasal process 
and the beginning of the fusion of the maxillary process with 
the lateral edge of the ventral end of the nasal septum (Vomer- 
polster). Posterior to this point, the nasal bridge is said to no 
longer form a primary palate, but a secondary one, and the oral 
nasal apertures, lying posterior to this secondary palate, are 
choanae reliquae, and represent remnants only of the pri- 
mary choanae. The maxillary process bounds laterally the 
choana of either side, and the bottom of the nasal groove opens 
directly into the angle formed by the inner surface of the maxil- 
lary process and the roof of the mouth. The furrow that forms 
the lateral boundary of the maxillary process has, in this trans- 
verse plane, become the bounding line between the maxillary 
