82 



The teeth of Bats are sharp-pointed and numerous, and usually there is a 

 gap between the incisors or cutting-teeth of the upper jaw ; this peculiarity is 

 shared with the Lemurs, and also with some of the Inseotivora, as for instance 

 the hedgehog. 



In the muscular system the chief peculiarity is the great enlargement 

 of the pectoral muscles ; this of course is in relation to the function of flight. 



Bats have the ordinary five senses, and are not blind as is sometimes sup- 

 posed ; the eyes are, however, very small and much obscured by hair. The sense 

 which seems to be most developed in Bats is that of touch ; and it is reasonably 

 supposed that the whole of the extended membrane conduces to the perfection 

 of that sense. 



Having now briefly run over the most marked structural features of Bats, 

 we may pass on to consider for a few moments their true position in the animal 

 kingdom. 



Amongst old writers Bats were frequently classed among birds, for the 

 simple reason that they, bats and birds, could fly ; the most cursory inspection 

 of a bat and a bird would show however their dissimilarity. Thus, a bird's wing 

 is formed of feathers growing out of the skin of the arm and fingers ; the hand, 

 again, of birds is reduced to two fingers which are joined together ; bats have 

 teeth ; these, and a thousand other differences, would at once show that bats and 

 birds were widely separated f lom each other. 



In the Reptile Class, there does, or rather there used to, exist a creature 

 •which must have presented some external resemblance to the Bats of the present 

 day — I mean the Pterodactyle. This animal, whose remains are found in the 

 Oolite Strata, had a membrane something similar to that of Bats, but an essential 

 difference in the construction of their wing from that of Bats consists in that 

 only the fifth digit of the hand is elongated, the other four being free and 

 clawed. Also the number of bones in the fingers increases from the thumb 

 outward to the fifth digit ; this is a character never found in Bats or any 

 other Mammals. 



Without going further into the details of structure we have seen enough 

 to prove that although there may be considerable functional anology between 

 Bats, Birds, and Pterodactyles, yet there is no real homology of structure. 



There is no doubt, therefore, that Bats are true INlammals ; but what rank 

 they may take among other Mammals is rather a difficult question to decide. 



All naturalists are, now-adajs, agreed in classing Bats as a distinct order 

 by themselves, under the name of Cheiroptera (wing-handed), but some place 

 this order next to the Quadrumana or Monkeys on account of the resemblance 

 which exists between Bats and Lemurs, especially in the teeth ; whilst others 

 arrange the Bats in a division with the Rodents (Rabbits, Mice, &c.) and the 

 Insectivora (Shrew, Mole, Hedgehog) on account of the similarity of their brains, 

 and teetl), and other internal parts of their structure. This latter arrangement 

 seems almost the best, and Bats seem most naturally placed next to the Insecti- 

 vora, being in fact Insectivora themselves. 



