CHIEOPTERA 



47 



Order II. CHIEOPTERA. Bats.^ 



Small, insectivorous, seldom fmgivorous, animals with very long fore-limbs, with 

 digits joined by a wing -membrane. Dentition complete, I reduced, C large, 

 generally with strong basal ridge, P pointed. M secodont or bunolophodont, 

 upper M tritubercular with V-shaped tubercles, lower M tuberculo-sectorial. Milk- 

 teeth rudimentary. Brain small and smooth. Two mammae in pectoral region. 



The bats form a specialised group of primitive insectivores. They 

 are distinguished from the true insectivores not only by the peculiar 

 development of their fore-limbs, but also by the generally shorter snout, 

 the well-developed sagittal crest, the marked postorbital constriction and 

 the completely ossified auditory bulla. 



The fore-limb is changed into an organ of flight (Fig. 74). The long 

 clavicle joins the sternum with the acromion of the shoulder-blade. The 



Fig. 74. 

 Vespertilio murinus Linn. Skeleton. (After Blainville.) 



humerus is slender and, in comparison with the size of the caput and the deltoid 

 ridge, very long. The length of the forearm exceeds that of the upper 

 arm, as a rule, by a third, often, however, it is twice as long. The ulna 

 is very much reduced. The proximal carpalia are fused. The . phalanges, 

 with the exception of the short, opposable thumb, become long, exceedingly 

 delicate structures, and are united with skin, which is also attached to the 

 hinder part of the body, to the tail, and to a long, ossified spur, extending 

 from the calcaneum. In contrast to the fore-limb, the hind-limb and pelvis 

 are weakly developed. The pes is pentadactyl, and the digits, all of equal 

 length, are clawed. 



Bats are divided into two groups : (1) Megachiroptera, which consist only 

 of large frugivorous forms, and (2) the small, insectivorous Microchiroptera. 



■* Gaillard, C, Maratniferes miocenes de La Grive St. Alban. Arch. Mus. Hist. Nat. Lyon, 

 voL vii., 1899. — Schlosser, M., Die Affeii, Lemuren, mid Chiropteren des europaischeu Tertiars. 

 Beitr. Palaontol. 5sterr.-Ung.. vol. vi., 1887. — Weithofer, A. Sitzber. Wien. Akad., math, 

 phys. CI. Bd. xcvi. , 1887. — Winge, H., Jordfundue eg nulevende Flagermus (Chiroptera) fra 

 Lagoa Santa. E. Museo Lundii. Kj0benhavn, 1892. 



