No. 2.] ON THE GUSTATORY ORGANS. 165 



the former traverse the mucous membrane, and open, somewhat 

 obliquely, on the free lingual surface ; while those of the latter 

 discharge into the trenches at their lower part. The mucosa 

 forming the body of the circumvallate papillae consists of three 

 main portions or lamellcX\ The central lamella is much the 

 largest, and overtops the other two. At its upper part it is 

 cleft into a number of secondary papilla;, the spaces between 

 which are filled to a common level with stratified epithelium. 

 The depressions between the lamellae not infrequently dip down 

 nearly to the base of the papillae, but they are for the most part 

 filled by epithelium. The average thickness of the stratified 

 pavement epithelium covering the papillae is about 0.045 mm. 

 This layer is thicker above than at the sides, but the difference 



is only slight. 



The bulbs of this gustatory area fill the middle third of the 

 papillary wall. Those of the outer wall of the trench are some- 

 what similarly placed. The bulbs, to all appearance, are in con- 

 tact by their edges, and, in the papilla, are disposed in a zone 

 of five tiers. Those embedded in the epithelium of the outer 

 wall are arranged in a girdle of four tiers. From horizontal 

 sections I estimated the mean number of bulbs in a tier of the 

 papilla at sixty, the mean number in a tier of the outer wall 

 being about seventy-five. The bulbs vary somewhat in size and 

 shape, but most of them have a fairly well-developed neck. 

 Their mean length is 0.049 "i"^- ^^^ ^^^^^ "^^^^ breadth 

 0.030 mm., they being a little smaller than in their eastern 

 congener, Lepus americanus. The papillae are well supplied 

 with nerves. Medullated fibres of the glosso-pharyngeus enter 

 the papillae at their base, and their finer (non-medullated) 

 branches form a delicate network in the mucosa directly be- 

 neath the bulb region. From the network fibrils enter the 

 bulbs, and also pass between them into the epithelium. 



The Lateral Gustatory Organs. — The superficial dimensions 

 of these papillae have already been given. Each foliate struc- 

 ture consists of fourteen folds, nearly all of which bear bulbs 

 on their lateral area. The folds are separated by narrow fur- 

 rows, having an average depth of 0.30 mm. The mucosa com- 

 posing the body of each fold is divided, as is usual in Lepus, 

 into three secondary folds or lamellae, the primary or central 

 lamella being taller and slightly broader than the two lateral. 



