188 EDWARD PHELPS ALLIS, JR. 
ist, ja beim Séuger diese Bildung einleitet. Mindere theoretische 
Bedeutung kann ich der Thatsache beimessen, dass die primitive 
Choane erst secondér durchbricht, und dass die Nasenhdéhle in ersten 
Stadium ihrer Entwickelung nicht durch eine Spalte, sondern durch 
eine solide Epithelleiste mit der Mundhdéhle in Verbindung steht. Es 
handelt sich hier nicht um principielle Verschiedenheiten. Ob die 
verbindung zwischen zwei Hohlriumen durch eine Epithelleiste oder 
durch eine Spalte hergestellt wird, kommt in vielen Fallen im Grunde 
auf dasselbe hinaus. 
The primary lips of embryos of the Amniota are represented, 
as they are in fishes, in the deeper portions of the mandibular, 
maxillary and fronto-nasal processes. 
In embryos of Amphibia the conditions, as described by 
authors, are totally different from those above considered. In 
the Gymnophiona the conditions are simpler than in the Urodela 
and Anura. In the former (Hypogeophis) a large lateral process 
(laterale Stirnfortsatz) is said by Hinsberg (02) to project across 
the oral edge of the nasal pit and to fuse completely, in its 
deeper portion, with the fronto-nasal process. The superficial 
portions of the two processes do not however fuse, this leaving, 
between the processes a shallow groove which extends from the 
nasal pit to a depression in the roof of the mouth (Gaumendach) 
which lies between the bases of the two processes; and it is im- 
portant to note that this shallow groove connects with the outer 
edge of the nasal pit, and not with its deeper portion. The fold 
of the secondary upper lip passes along the middle line of the lat- 
eral process and continues beyond it across the fronto-nasal process, 
the fold thus lying between the nasal opening and the depression 
in the roof of the mouth. In slightly older embryos the lateral 
and fronto-nasal processes project above the shallow groove 
described above and there again fuse with each other, thus 
enclosing the groove beneath the epidermis, the nasal end of 
the groove becoming a closed canal surrounded by epithelial 
tissues, and its oral end becoming a solid cord of epithelial tissue. 
The processes do not so project and fuse with each other above 
the depression in the roof of the mouth, that depression still 
persisting between the bases of the processes. In still older 
embryos the lumen in the epithelial cord is prolonged orally, 
