The Pharj'ngeal Pouches in the Mammalia 245 



poucli ; Mn. F., manubrial fossa ; S. Pi., sinus piriformis ; z., indentation 

 between tympanic pouch and tonsillar fold. X '^j reduced Vs. 



Fig. 24. — Dorsal view of pharynx in same specimen, x 60, reduced Vb- 



Fig. 25. — Ventral view in same specimen. X ^' reduced V5. 



Fig, 26. — A portion of the pharynx, including tympanic pouch and tonsillar 

 fold in a 20 mm. pig, viewed from the posterior side. pm. f., post-manubrial 

 ridge; ps. f., post-salpingeal fold. Other symbols as before, x 30, reduced %. 



Fig. 27. — The same structure as in Fig. 26, viewed from anterior side. 

 Symbols as in preceding figure. X 30, reduced Vs- 



Fig. 28. — Thymus and associated parts in the same animal, front view, 12, 

 hypoglossal nerve ; other symbols as before, x 30. 



Fig. 29. — Lateral view of pharynx in a 24 mm. pig. Harvard medical col- 

 lection. X 60, reduced Ve- 



Fig. 30. — Dorsal view of the same pharynx as in Fig. 29. X 60, reduced Vb- 



Fig. 31. — Left thymus of same animal with carotid gland and prsecervical 

 appendix. Cv. C, cervical cord ; F. Pc, hook-shaped portion of fundus priecer- 

 vicalis; F. Pc. V., ventral segment of the fundus — this is .ioined to F. Pc. by a 

 narrow connective extending over the outer surface of the carotid gland, but 

 hidden from view in figure by the oblique position of the latter, x ^'^' 

 reduced %. 



Fig. 32. — Lateral view of pharynx in a 32 mm. pig. Harvard medical col- 

 lection. G. Ep., glosso-epiglottic fold ; Mk. F., Meckelian fossa ; Mn. F., 

 manubrial fossa ; other symbols as before. X 60, reduced Vb- 



Fig. 33. — Dorsal view of same structure as in Fig. 32. The naso-pharynx 

 is represented as cut across, thereby showing its Interior. X 30, reduced %. 



Fig. 34. — Left carotid gland and associated prsecervical mass and hypo- 

 glossal nerve in 32 mm. pig, anterior view. For symbols, see i'ig. 31. X 80, 

 reduced V^. 



Fig. 35. — Right carotid gland and associated parts in the same animal, 

 posterior view. The carotid gland is represented as sectioned in the plane of 

 the paper. The prgecervical mass has divided into two parts, internal, F. Pc, 

 and external, Th. S. The latter is the thymus superficialis of Kastschenko. 

 X 80, reduced %. 



Fig. 36. — Part of a sagittal section of the head of a 9 mm. pig, showing 

 origin of carotid gland. C. Gl., carotid gland ; Per., pericardial cavity. Other 

 symbols as in preceding figures, x 5^' reduced Vs. 



Fig. 37. — Part of a transverse section of a 13 mm. pig (M') showing the 

 final separation of the first pouch from the skin. Coch., cochlea; Ch. Ty., 

 chorda tympani ; D. A. 1, dorsal apex with the part by which the pouch is last 

 connected with the skin; Impr., impressio cochlearis ; Ph. G. 1, the first 

 pharyngeal groove, its undulating course causes it to be sectioned twice in 

 the section ; V. D. 1, ventral diverticulum of first pouch. X 50, reduced %. 



