DEVELOPMENT OF THE SKULL OF EMYS 737 



describes the septum as not extending as far forward as I have 

 found it, so that the two fenestrae narinae are less perfectly sepa- 

 rated from each other. 



Of special interest in connection with the septum nasi is a long 

 rodlike cartilage* which, at its posterior end, is continuous with the 

 septum by the crista longitudinalis septi; it extends anteriorly, 

 parallel to the crest and separated from it by a narrow space, 

 and ends freely a short distance behind the anterior margin of 

 the septum. The glandula nasalis media is medial and ventral 

 to this rod while lateral to it and supported by it is the median 

 fold of the olfactory sac which separates the pars olfactoria from 

 the pars respiratoria. To this rod I would give the name pila 

 supraglandularis (p.sg., fig. 13). 



In an embryo of 13.5 mm. carapace length the pila supraglan- 

 dularis is continuous at its posterior end with the floor of the cap- 

 sule immediately in front of the foramen praepalatinum (figs. 16 

 to 18). From this relation it follows, as Seydel has shown, that 

 the foramen praepalatinum opens into the olfactory capsule 

 directly in a dorsal direction behind and in a lateral direction 

 further forward beneath the pila supraglandularis. Later in 

 embryonic development (16 mm. carapace length) the pila supra- 

 glandularis fuses along its whole length with the crista longitu- 

 dinalis septi and forms a sloping roof extending ventro-laterally 

 from the septum dorsal to the glandula nasalis media. 



The glandula nasalis media lies with its posterior end in the 

 anterior half of the foramen praepalatinum and extends obliquely 

 forward and dorsally, parallel to the septum, beneath the pila 

 supraglandularis. The gland opens at its anterior end into the 

 olfactory sac ventral to the anterior end of the crista longitudinalis 

 septi. 



The cartilago paraseptalis is a short plate forming the ventro- 

 median boundary of the fenestra basalis. It is continuous in 

 front with the floor of the capsule which exhibits ventrally in its 

 posterior part a moderately deep groove between its two halves. 

 The cartilago paraseptalis accordingly exhibits a ventro-median 

 and a dorso-lateral face at its anterior end, but toward its poste- 

 rior free end it is rotated slightly so that the faces are directed 



