942 



folds, running transversely from a mesial raphe towards the lateral 

 limits of the organ. 



The circumvallate papillae, of which there are commonly two 

 pairs, an anterior and a posterior, are situated well-back on the dor- 

 sum 1). They are large, rather prominent, and generally lobate. The 

 posterior pair are 8 mm from the base of the tongue and 2,5 mm 

 from each other. The anterior pair are 1—2 mm distant from the 

 posterior and are 5 mm apart. At each side of the tongue, imme- 

 diately in front of the arcus glosso-palatinus, is a papilla foliata. 

 The two papillae are rudimentary in so far as they possess no taste 

 bulbs. They consist of ten or more somewhat irregular folds, which 

 are separated by well-defined and fairly symmetrical furrows. About 

 the base of the folds glands are fairly abundant. It is not unlikely 

 that further search may reveal the presence of bulbs in this region, 

 although I failed to find any trace of them in my specimens. An 

 examination of many sections also failed to show true bulb-like forms 

 in the epiglottis or in any part of the larynx. 



The circumvallate papillae which I examined were all more or less 

 constricted at their upper part. Below the constriction they measure 

 from 0,60 to 0,90 mm in diameter. Each papilla is encircled by a 

 narrow trench which is of uniform breadth, save at the point facing 

 the constriction, where it is much wider. Serous glands are very nu- 

 merous, and their ducts open into the trench at its base and sides. 

 The epithelial covering of these papillae, and of the region round 

 about them, is quite thin, only averaging 0,04 mm in thickness. 



The taste bulbs are not very plentiful in Putorius vison. 

 They are disposed at the sides of the papilla in a girdle of 8 to 12 

 tiers. They rarely occur on the outer wall of the trench, and none 

 were detected in the epithelium of the free upper surface. Judging 

 from horizontal sections there appear to be about fifty bulbs in a tier. 

 If we allow for ten tiers, we shall have five hundred bulbs for each 

 papilla. The bulbs do not vary much in size and shape, and are 

 without a well-defined neck. They measure 0,039 mm in length, their 

 greatest transverse diameter being 0,024 mm. Non-medullated nerve- 

 fibres stream into the papilla, and their terminal branches run up- 

 wards towards the summit and laterally towards the sides containing 

 the taste bulbs. 



1) Occasionally I have found on the tongue of this mammal three 

 pairs of well-developed circumvallate papillae. 



