CHIROPTERA 17 



The crown pattern of the upper molars, often reduced in size 

 from behind forwards, is formed by three main cusps — the inner 

 anterior (the protocone), the outer anterior (the paracone), and 

 the outer posterior (the metacone) — and at the extreme outer 

 edge three small cusps — the anterior (the parastyle), the median 

 (the mesostyle), and the posterior (the metastyle). The styles 

 and cones are connected by conspicuous ridges — the com- 

 missures — running respectively from parastyle to paracone, 

 paracone to mesostyle, mesostyle to metacone, and metacone to 

 metastyle. The result is a conspicuous W-pattern, the varia- 

 tions in form of which are of much systematic importance ; this 

 pattern is not obscured by the presence of an inconspicuous 

 inner posterior hypocone. The second molar is usually the 

 largest, the third always the smallest (Plate II., Fig. i). 



The lower molars correspond to the upper in size, but the 

 posterior is relatively larger. There are five cusps — the outer 

 anterior (the protoconid), the inner anterior (the paraconid), the 

 inner median (the metaconid), the outer posterior (the hypoconid), 

 and the inner posterior (the ectoconid). These teeth resemble 

 the outer higher portion of the upper molars reversed with the 

 two segments of the W disconnected. In the third lower molar 

 the posterior segment is usually smaller than the anterior. The 

 most prominent cusps are, in the first two upper molars the 

 metacone, in the third upper the paracone, in the lower molars 

 the protoconid^ (Plate II., Fig. i). 



The key to the teeth and skulls at the end of this article 

 will probably be found useful. 



The colours of bats, although not usually bright as com- 

 pared with those of many other mammals, include as exceptions 

 perhaps the brightest tints of the whole class. Although to a 

 great extent creatures of the night, their external coloration is 

 evidently subject to laws similar to those which govern that of 

 diurnal mammals. 



The general tints are due often, as in Leisler's Bat, to the 

 tips of the hairs, from which the bases differ in colour. In 

 other cases, as in the Noctule, the hairs are almost or entirely 



^ For further details see Herluf Winge, "Jordfundne og nulevende Flagermus 

 {Chiroptera), fra Lagoa Santa, Minas Geraes, Brasilien," from E. Mtiseo Lundii, vol. 

 ii., paper i, 1893. 



C 



