Tuckerman.] 
474 
[Feb. 19, 
tatory papillae themselves. In the highly ancestral Ornithorhynchus 
we find the primitive form of the circum vallate papilla. At the 
posterior region of the tongue of this mammal are two pairs of 
gustatory areas. The anterior pair lie below the surface in a fur- 
row, the floor of which is invaginated upwards into a ridge. The 
ridges of the posterior pair reach the surface. The ridges of both 
areas bear taste-bulbs over the whole of their convexity. Ascend- 
ing in the scale, we find in the gustatory ridges of Belideus struct- 
ural characters which are common to both the circumvallate type 
of taste-area and the bulb-bearing ridges of Ornitliorliynclius. The 
ridges of Belideus furnish us with an intermediate stage in the pro- 
cess of development of the former from the latter, the more re- 
cent from the more primitive form of taste-area. In the higher 
mammals it is probable that in some cases, the number of the cir- 
cumvallate papillae may be added to by direct development from 
fungiform papillae. The hypothesis, however, that a fungiform 
type of papilla is always a forerunner of the circumvallate form, 
and that all circumvallate papillae are but modifications of the 
fungiform type, is, I think, no longer tenable. 
In marsupials and in some rodents, as the squirrels, beaver and 
prairie-dog, there are but three papillae of the circumvallate form, 
and they are nearly always arranged in a triangle, the apex of 
which looks towards the epiglottis. Frugivorous bats, apes and 
monkeys, have also three circumvallate papillae similarly arranged. 
Edentates, hares and rabbits, moles and shrews, usually have two 
circumvallate papillae, while the musk-rat and pouched gopher have 
but one. Among the domesticated animals the horse and pig have 
each two circumvallate papillae, the calf and sheep twenty to thirty 
each, and the goat twelve. The elephant has six and the giraffe 
fifty. In the Carnivora the number varies from two to twenty. 
Man has usually eight, and sometimes twelve, but never less than 
four. The only mammals in which the circumvallate papillae are 
apparently wanting, as far as known, are the Hyrax , or coney of 
“Scripture,” and the guinea-pig. Both of these forms, however, 
possess the lateral organs of taste (papillae foliatae), those in the 
Hyrax being very beautifully developed. 
The papillae foliatae, or lateral organs of taste, were described by 
Albinus in 1754 as degenerated papillae. In 1832 Rapp observed 
on the hinder part of the tongue in different mammals a series of 
transverse fissures lying close together, and found them also in 
