330 The Alligator and Its Allies 
the tail) of this age is shown in Figure 23a. In the 
head region the section is nearly median, while the 
posterior part of the body is cut slightly to one 
side of the middle line. At the tip of the now 
well-developed snout is seen one of the nostrils (an), 
cut through the edge; its connection with the com- 
plicated nasal chamber (n) is not here seen, nor is 
the connection of the nasal chamber with the 
posterior nares (pn). The pharynx (ph), is ante- 
riorly connected with the exterior through the 
mouth (m) and the nares, while posteriorly it 
opens into the cesophagus (ve); the trachea (ta), 
though distinct from the cesophagus, does not yet 
open into the pharynx. In the lower jaw two 
masses of cartilage are seen, one near the sym- 
physis (mk) and one near the wall of the trachea, 
doubtless the rudiment of the hyoid. The deep 
groove back of the Meckel’s cartilage (mk) marks 
the tip of the developing tongue, which here forms 
the thick mass on the floor of the mouth cavity. 
Dorsal to the pharynx a mass of cartilage (se) 
is developing in the sphenethmoid region. This 
being a median section, the ventricles of the fore- 
(fb), mid- (mb), and hindbrain (hb) are seen as large 
cavities, while the cerebral hemispheres (ch) appear 
nearly solid, only a small portion of a lateral 
ventricle showing. The paraphysis (epz) is cut a 
little to one side of the middle and so does not show 
its connection with the brain. At the base of 
the brain the infundibulum (zz) is seen as an elon- 
