DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 201 



Ventrad of the alveolingual region is situated the lingual nerve and 

 the submaxillary ganglion. The nerve passes obliquely ventrad of the 

 lingual sulcus, approximately at the junction of its intermediate and 

 caudal segments, thence ascending into the tongue accompanied by 

 a prolongation of the ganglion (Fig. i6, 49). The point where the 

 fibers of the nerve he vertically beneath the sulcus is a convenient 

 and classic landmark in this region and is termed the lingual crossing; 

 in later stages, where the nerve crosses in two branches, having divided 

 lateral to the sulcus, the larger caudal branch is referred to. Owing 

 to the large size of the ganglion and its prolongations, only the nerve 

 fibers are had in view in measurements reckoned from this point. 



The marginal cavity forms a winglike extension of the mouth 

 laterad from the alveoUngual region to the buccal sulcus. The 

 mesal limit corresponds to the crest of the palate process which is 

 sagittal for the greater part of its length, turning towards the median 

 hne only at its cranial extremity, and that to a very shght degree 

 (Figs. 15, 16, 17). Owing to the divergence of the buccal sulci, the 

 cavity has the shape of an irregular triangle with its base craniad, 

 truncated at its caudal extremity where it joins the pharynx. The 

 roof is formed by the palate and ma.xillary processes, the floor in its 

 whole extent by the mandibular process. The composition of the 

 roof permits a di\'ision of the cavity into a median zone, the palato- 

 mandibular plane, and a lateral, the maxillomandibular. The 

 lateral border of the palate process is marked by a concavity, subject 

 to some variation in its definition, but becoming more distinct and 

 sulcuslike as development proceeds and attaining its ma.ximum just 

 prior to the closure of the palate in embryos of 19 to 20 millimeters. 

 This is the ectopalatine sulcus (Figs. 97, 100-103, 62). It is nearly 

 parallel to the crest of the palate process, haxing a course in general 

 sagittal with a sUght mesal deviation of its cranial extremity. Caudad 

 it approaches the buccal sulcus, but becomes very shallow and ill 

 defined. At no stage in the cat does it distinctly reach the buccal 

 sulcus, as it does in the human embryo (cf. Part IT Figs. 19, 24, J4). 

 In embryos of lo-ii millimeters the ectopalatine furrow can be fol- 

 lowed to the plane of the mandibular nerves. Here the orbital fold 

 is forming at the expense of the extreme border of the marginal cavity 



(Figs. lo-ii). In embryos of 11.5 and 12.5 millimeters the fold has 



