DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 21 5 



rapidly mesad and the inferior dental anlage is already separate. On 

 the roof the thickening gradually diminishes towards the palate process; 

 as yet the superior dental anlage is but faintly indicated. Close to 

 the angulus oris a small epithelial crest is attached to the buccal sulcus 

 for a few sections (Fig. 24). Its presence suggests the occurrence of 

 some degree of fusion at the angulus, the crest being a remnant of the 

 epithelium destroyed in the process. It is present constantly in em- 

 bryos of about this stage, being most marked immediately behind the 

 angulus and thence rapidly diminishing caudad. A similar crest is 

 sometimes attached to the furrow on the surface which intervenes 

 between the maxillary and mandibular processes. Their bearing upon 

 the question of fusion at the angulus has already been discussed. 

 Near the orbital angle the lumen of the buccal sulcus is reduced to a 

 narrow fissure (Fig. 26), which in the next section is obhterated (Fig. 

 27) and the pars lata is formed. The union of the layers so as to cut 

 off a portion of the fissure from the oral cavity in Fig. 26 is unusual and 

 may be due to obliquity in the section. The pars lata is broad at its 

 cranial extremity and though it becomes somewhat broader in 

 the following sections (Fig. 27) shows as yet no tendency to taper into a 

 point craniad. It narrows abruptly where the buccomasseteric nerve 

 comes into contact (Fig. 2q, 6g) here sending a short process caudad 

 on the lateral aspect of the nerve (9). In its inception this lateral 

 process appears as a mere bulge beyond the nerve. In later stages its 

 variable length suggests some independent growth. The pars cylin- 

 drica (Figs. 29, 30, 8) is circular in section, the center somewhat pale, 

 the separating sulci well defined. Caudad it accurately surmounts the 

 buccal sulcus (Fig. 30) ; its position is fundal. Near its junction with 

 the pars lata the inclusion has begun to undergo a dislocation ventrad. 

 The epithelium of the mouth mesad to the dorsal separating sulcus 

 is convex, suggesting here a more active growth and consequent 

 tendency to fold, as contrasted with the ventral wall of the sulcus. 

 The sulcus is, in fact, in process of forming a new fundus on a higher 

 level. In later stages the ventral displacement of the inclusion be- 

 comes marked and affects its whole extent. This is a good illustration 

 of the tendency of the oral anlages to shift from a fundal to a parietal 

 position. In all cases it appears to be the sulcus which is active and 

 produces a new fundus to one side of the flange, as though its presence 



