X.-^ THE MAMMALS OF INDIA. 



large and full, cind several of the Carnivora have a very keen sight, 

 though not so acute perhaps as that of many raptorial birds. The 

 eyelids in most are double as in Man, but in some of the lower forms 

 a remnant of the nyctitating membrane is also met with. A lachrymal 

 apparatus exists in most animals except the Cetacea. 



The sense of hearing attains its greatest perfection in Mammals, 

 and an external ear is present in most ; it is generally mobile, to assist 

 in conveying and concentrating the sound from every direction. The 

 internal ear is imbedded in the petrous portion of the temporal bone, 

 and is remarkable for the development and complexity of the cochlea. 

 The tympanic cavity is large, and communicates with the pharynx by 

 the eustachian tube. The communication between the membrane of 

 the tympanum and the inner ear, which in the other vertebrates takes 

 place by one ossicle, here consists of four. 



Owing to the fleshy nature and mobility of the tongue, the sense of 

 taste is much greater than in any other animals. 



The leading peculiarity of the class of Mammals, viz., the nourish- 

 ing of the new-born young with milk, has been already alluded to. 

 The milk is secreted by the mammary glands, and these vary in 

 number and position, being most numerous in the more prolific 

 races. In most animals they are ventral, inguinal in many, and 

 pectoral in a few. They vary in number from two to twelve. The 

 yelk of the ovum which suffices for the nourishment of the young of 

 Reptiles and Fishes, only affords a very small amount of nutriment 

 to the Mammalian ovum, when expelled from the ovary, and the 

 fcctus is supported in the uterus by the blood of the mother, conveyed 

 by means of a vascular connection, called the placenta, the shape and 

 situation of which, within the uterus, varies considerably. In one 

 tribe of animals, however, the Marsupials, the young are expelled 

 from the uterus at a very early period of development, and receive no 

 nourishment beyond that derived from the yelk, no placenta being 

 formed. 



The young of several animals are born blind, others with their eyes 

 open. Most are helpless at first, whilst a few are able to run about 

 very shortly after birth ; some attain their full size in a few months, 

 others take several years. 



