CHIROPTERA 



647 



the RhinolophidcK, the only family of insectivorous Bats wanting the 



tragus, the auditory bullse reach their greatest size, and the highly 



sensitive nasal appendages their highest development; and that in 'the 



typical group of the Molossince the ear- 



conch is divided by a prominent keel ; 



and the antitragus is unusually large 



in those species in which the tragus is 



minute (see Fig. 298, a). In the frugi- 



vorous Bats the form of the ear-conch 



is very simple, and but slightly variable 



throughout the various types. 



In all Bats the ears are extremely 

 mobile, each moving independently at 

 the will of the animal. This has been 

 observed even in the frugivorous Ptero- 

 podidce, in which the peculiar vibratory 



. . j -j FIG. 298. Headof JlfoZossttsj/faactntw. 



movements first noticed in Artibeus (FromDobson,proc.zoo.Soc.i876.) a, 



also be Seen when 



Antitragus ; 6, keel of the ear-conch ; c, 



may 



the animals are alarmed. 



The opening of the mouth is anterior in most species, but in 

 many it is inferior, the extremity of the nose being more or less 

 produced beyond the lower lip, so much so indeed in the small 

 South- American species Rhynchonyderis naso as to resemble that of 

 the Shrews. The lips exhibit the greatest variety in form, which 

 will be referred to under each family. The absence of a fringe 

 of hairs is characteristic of all fruit- eating Bats, and probably 

 always distinguishes them from the insectivorous species, which they 

 may resemble in the form of their teeth and other respects. 



The oesophagus is narrow in all species, and especially so in the 

 sanguivorous Desmodont Phyllostomatidce. The stomach presents two 

 principal types of structure, which correspond respectively to the 

 two great divisions of the order, the Megachiroptera and the Micro- 

 chiroptera ; in the former (with the exception of Harpyia) the 

 pyloric extremity is more or less elongated and folded upon itself, 

 in the latter it is simple, as in the Insectivora Vera ; a third 

 exceptional type is met with in the Desmodont Phyllostomatiifn; 

 where the left or cardiac extremity is greatly elongated, forming a 

 long narrow caecum-like appendage. The intestine is comparatively 

 short, varying from one and a half to four times the length of the 

 head and body, being longest in the frugivorous and shortest in the 

 insectivorous species. Only in Rhinopoma microphyllum and Mega- 

 derma spasma has a very small caecum been found. 



The liver is characterised by the great size of the left lateral 

 lobe, which occasionally equals half the size of the whole organ ; the 

 right and left lateral fissures are usually very deep ; in the Mega- 

 chiroptera (Harpyia, excepted) the Spigelian lobe is ill-defined or 



