230 Henry Fox 



carotid gland and the epithelial plate now forming the dorsal end of 

 the thymus, but representing originally the peripheral body of the third 

 pouch (D.Pl.). With the exception of its vesicula, the fundus is with- 

 out a distinct lumen. The vesicula originates at its vent ro -internal 

 angle, then bends backwards and terminates, as before, in the anterior 

 part of the ganglion of the vagus. 



In the 20 mm. pig the ductus has shrunken to a mere remnant (Fig. 

 28, f. pc). The remainder of the fundus prgecervicalis, excepting the 

 vesicula (v. pc), forms a flattened band, which is closely wedged in 

 between the lateral surface of the carotid gland (c. gl.) and the hypo- 

 glossal nerve (xii), over which its free end curves after the manner of 

 a hook. At the lower posterior side of the carotid gland it expands to 

 form the vesicula, which retains the same relation to the ganglion of 

 the vagus as hitherto. The dorsal extremity of the thymus is wedged 

 in between this part of the fundus and the carotid gland (Fig. 45), 



It will be noticed that the fundus now has an ascending course. 

 Beginning at its vesicular extremit}^, it extends diagonally upwards and 

 outwards over the lateral surface of the carotid gland to the upper 

 side of the hypoglossal nerve, over which it curves like a hook. This 

 condition, as I shall attempt to show presently, is to be correlated with 

 the changes in position of the nerve mentioned. 



The condition of the fundus prsecervicalis is essentially similar in a 

 cat of 10.7 mm. The left ductus, however, is considerably longer than 

 that on the opposite side. 



In a cat of 15 mm. the ductus has disappeared. The rest of the 

 fundus (Fig. 63, F.Pc.) is coiled over the top and back of the carotid 

 gland. It shows a distinct vesicle, located on the posterior surface of 

 the gland. 



The pig of 24 mm. shows the fundus as a much coiled, mostly solid, 

 band. A slight lumen persists in the vesicula prsecervicalis, which Is 

 now located on the postero-inferior surface of the carotid gland, some 

 distance in front of the ganglion of the vagus. From this part the 

 fundus curves upwards over the outer surface of the gland as an ex- 

 ceedingly thin, flattened ribbon, which at its dorsal extremity expands 

 slightly into the hook-shaped process, which, as before, is curved out- 

 wards over the hypoglossal nerve (Fig. 31, F.Pc. and F.Pc.V.). 



In a pig of 25 mm. the condition of the fundus is very similar to 

 that just described. The part of it adjoining the vesicula is somewhat 

 broader and is sub-divided into a number of small lobules. 



