246 Henry Fox 



Fig. 38. — Part of a transverse section of the region of the third pouch in a 

 13 mm. pig (ivr). d. pi., dorsal lamina of the thymus. Other symbols as in 

 preceding figures, x 50, reduced i^. 



Fig. 39. — Similar section slightly posterior to last. ph. g. 2, second pharyn- 

 geal groove. X 50, reduced I/2. 



Fig. 40. — Section posterior to last, passing through fundus prtecervicalis, 

 f. pc. ; or 3, ectodermal organ of third pouch ; pul., pulmonary artery, x 50, 

 reduced 1'2. 



Fig. 41.- — Part of a transverse section through the head of an 18 mm. pig, 

 M^ The section passes close to the oral extremity of the tympanic pouch, 

 al. f., alveolo-lingual fold ; G. Gas., gasserian ganglion ; s. p. c, superior 

 petrosal nerve ; 5^ inferior maxillary division of trigeminal. X 50, reduced i/^. 



Fig. 42. — Part of a similar section, a few sections behind the preceding. 

 X 50, reduced 1/2. 



Fig. 43. — Similar section, posterior to preceding, d. 1. s., dorso-lateral wall 

 of tympanic pouch ; G. Gn., geniculate ganglion ; p. g. 1, first pharyngeal 

 groove. X 50, reduced %. 



Fig. 44. — Similar section in region of the dorsal apex of the tympanic 

 pouch. G. Au., auditory ganglion ; hy., hyoid ; thr., thyroid cartilage ; 7, main 

 trunk of facial, showing its two divisions, the outer being the basal portion 

 of the chorda tympani. x 50, reduced %. 



Fig. 45. — Section near hind margin of tympanic pouch. The latter lies in 

 the upper right-hand corner, dc. t., duct of lateral thyroid ; f . pc, fundus 

 praecervicalis — the dorsal plate of the thymus lies between this and the 

 carotid gland, c. gl. x 50, reduced %. 



Fig. 46. — Section slightly posterior to preceding, gl. t., glandule thyroid- 

 ienne ; ps. f., post-salpingeal fold ; v. pc, vesicula prrecervicalis. x 50, 

 reduced %. 



Fig. 47.- — Part of a transverse section of the head of a 25 mm. pig, M^ 

 The section passes near the front end of the tympanic pouch, v. f., vestib- 

 ular groove. X 50, reduced %. 



Fig. 48. — Similar section near anterior edge of submeckelian fold in same 

 animal. Mk. f ., Meckelian fossa ; s-m. f., submeckelian fold ; vis., ventro- 

 lateral wall of tympanic pouch. X 50, reduced % 



Fig. 49. — Section through middle part of the submeckelian fold in same 

 animal, e. an., external auditory meatus. X 50, reduced %. 



Fig. 50. — Section slightly posterior to the point where tympanic pouch and 

 pharynx are connected, pig, 25 mm. The post-salpingeal fold projects from 

 the sides of the pharynx immediately internal to the tympanic pouch, mn., 

 manubrium of the malleus. X 50, reduced %. 



Fig. 51. — Section through the posterior segment of the tympanic pouch, 

 p. m. f., post-manubrial ridge; s. t. ty., sulcus tensoris tympani; t. s., tensor 

 muscle ; v. m. r., ventro-mesial border. X 50. reduced ^2- 



