^"1893^''] PROCEEDINGS OF THE NATIONAL MUSEUM. 15 



tli<^ premaxilla), afford bases for some character.s of minor value. Tlie 

 length of the infra-orbital canal and the peculiarities of the outer wall 

 of the canal are of interest. In Arfihens the canal is lon<>" and for the 

 moat part smootli externally, as in Gaiiis, while in the fauna generally 

 it is short, as in Felis, and is often elevated. 



Tlie hard palate maybe either in the main axis of the skull, as in most 

 forms, or detlected upward and forward. The characters furnished by 

 the i)terygoid i^rocesses, the palatal plates, are here as useful as in 

 other mammalian groups. The premaxilhe are rarely firmly united to 

 one another. When they are so united, as in Phyllostomidjii and JMo- 

 lossi, the median incisors are disposed to be contiguous. When they are 

 not united, a large median interspace separates them and is continuous 

 with the vacuity which in other mammals represent the incisorial for- 

 amen. Theijresence or absence of the spheuo-palatine foramen is used 

 in some grouj)s, as Molossi and in Plecoti, in separating genera. The 

 dispositi(m of the turbinals is also of interest, the peculiarities of the 

 arrangement being definitive of the families as established on other 

 structural characters. If in mammals generally an outer and an inner 

 turbinal group is recognized, then in the bats we have a median lamina 

 Avhich bears ui)on its inner surface one or more scrolls (endotnrbinals), 

 and an outer lamina with much simpler ac(tessories (ectoturbinals). 

 The sim[)lest arrangement of the turbinals is seen in the Nycteridie and 

 Rhinolophi(he, the most complex in Pteropida\ In NatalKS alone is 

 the ectoturbinal rudimental (U' absent. (Bull. Mus. Comp. Zool., Feb., 

 1880.) 



In addition to the peculiarities of the masseteric impression on the 

 lower Jaw, already noticed, characters are furnished in the height of the 

 coronoid process and the degree of deflection as well as the size and 

 shape of the angle. The post-symphysal spine which is conspicuous 

 in some extinct forms has not been seen l)y me in any of the extant 

 forms, and I have examined most of the genera of the order. 



The shortening of the face, pari passu, with reduction of teeth, is seen 

 in Carnivora. The tendency is seen in Vesperugo, and in bats gen- 

 erally. In VespertiUo the shortening of face is accompanied by dis- 

 placement inward of the premolars. In a mechanical sense it amounts 

 to the same as reduction in number. In pteropine bats a remarkable 

 liersistence of facial length remains, while the disx)osition to reduction 

 is evident. One may conclude from the instance last named that the 

 shortening of face and reduction of teeth are independent. The same 

 is true of the Ungulata. 



In A^a/^/j;/(fr the lower jaw closes in front of the upper. The lower 

 canines articulate with the anterior surfaces of the upper laterals their 

 entire length. The upper canines are free, /. e., do not articulate with 

 anything. 



Vertebral column. — The vertebral column is without large processes 

 other than the h.emopophyses which are well developed in the cervical 

 reuiou. 



