DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 309 



alveobuccal glands and may, therefore, be directly compared with the 

 superior labial series of reptiles. 



6. The inferior alveolabial glands are a series of simple sprouts in 

 the course of the sulcus of the same name, and are equivalent to the 

 inferior labial glands of reptiles. 



7. Reichel interpreted the parotid as equivalent to an hypertrophied 

 gland of the superior labial series. As the segment of the buccal sulcus 

 from which it arises is not present in sauropsida, this homology re- 

 quires quaUiication. In view of the continuous placode which occupies 

 the marginal cavity of mammalian embryos, and the evolution of sepa- 

 rate anlages incident to its expansion, it would seem that in this 

 placode was contained material equivalent to both dorsal and ventral 

 alveobuccal sulci and their derivatives ; that, in general, expansion 

 and separation of the anlages precede their activation, but that the 

 parotid, being accelerated, develops in the fundus of the buccal sulcus 

 out of material which has not yet been absolutely assigned either 

 to the dorsal or the ventral gland line, and appears, therefore, onto- 

 genetically as a neomorph of intermediate position, yet in its subse- 

 quent shift to a dorsal parietal position and in ultimately coming to 

 open upon a common stomal ridge with the orbital glands, it manifests 

 its closer affinity to the dorsal line, which is also reflected in the less 

 degree of expansion of the dorsal Wangenstreifen, as compared with 

 the ventral. It should, therefore, be interpreted as a displaced portion 

 of the dorsal series, owing its inception and independence to processes 

 incident to formation of the cheek and consequent lengthening of the 

 buccal sulcus of the mammaha, 



8. The glands of the alveolingual region are the submaxillary, the 

 greater subUngual, and the lesser sublinguals. The submaxillary anlage 

 appears as a low keel of epithelium at the fundus of the lingual sulcus, 

 a persistence of the mesal border of the primitive placode. A flange 

 is then formed in the segment of the sulcus caudal to the lingual nerve, 

 and the keel is carried ventrad as its free border. The flange becomes 

 triangular, and proliferation is initiated at its free angle ; there results a 

 distal free-growing sprout and the formation of a crest proximad, which, 

 advancing along the flange, reaches the fundus of the sulcus. Later, 

 as the sulcus deepens the lengthening crest assumes a parietal position 

 in its lateral wall. The duct is formed by the constriction and separa- 



