322 Jacob Parsons Schaeffer. 
the early fusion of some of the processes (Nebenmuscheln). 
The space immediately inferior to his ‘‘untere Nebenmuschel”’ 
or the space he designates as the ‘‘ Recessus inferior”’ of his first 
chief furrow, is the infundibulum ethmoidale—the exact place 
of the primary maxillary pouching. 
At this juncture mention must be made of the primary pouch- 
ing of the sinus frontalis in order to interpret later conditions in 
connection with adult fronto-maxillarv relations. It will be 
remembered that the furrow from which the maxillary pouch 
evaginates has ascending and descending rami, and that from 
the descending ramus the maxillary evagination takes place. 
The ascending ramus of this furrow widens and pushes ventrally 
and superiorly. Turner says: 
It is generally held that the frontal sinus commences to develop at 
the end of the first or the beginning of the second year of life, as an up- 
ward expansion of the ethmoid cell labyrinth. 
Hartman quotes Steiner for the following: 
Der erste Anlage der Stirnhéhle ist in der Anlage des Knorpeligen 
Siebbein-labyrinthes gegeben mit der Entwickelung der zelligen Raiume 
des vorderen Siebbeinlabyrinthes beginnt auch die der Stirnhdhle, denn 
letztere stellt eben nur die Ausdehnung der vorderen Siebbeinzellen 
nach oben dar. 
Hartman makes the following statement: 
Aus dem aufsteigenden Ast der ersten Hauptfurche bildet sich durch 
oberflachliche Verwachsung eine sackartige Bucht, der Recessus ascen- 
dens od. R. frontalis, die Stirnbucht. Aus der Stirnbucht entwickelt 
sich die Stirnhohle. 
The embryos studied showed evidence of a slight pouching at 
the superior and ventral end of the primitive meatus nasi medius. 
This doubtless corresponds to the ‘‘Recessus frontalis” of the 
first chief furrow of Hartman and Killian. 
According to Killian’s commendable work there are three 
processes and four furrows on the lateral wall of the recessus 
frontalis, which are designated by him as ‘‘Stirnmuscheln und 
Stirnfurchen,”’ respectively. The processes, according to Killian, 
