TLASTIC CHARACTERS. 



ri carl}- vertical oroulyslightlvproclivoiis. A somewhat, or even much, 

 liighcr degree of proclivity is seen in Fhrotes, Epomops, SiJucrias, 

 all Macrofjlossiiw; except Eomjcteris, and in Harpyioivjctens. 



Interconnection of branches. — In the large majority of Fruit-bats 

 the right and left alveolar branch of the preraaxillte are in simple 

 contact anteriorly, the suture between them being permanent. 

 In certain genera, however, they become, at an early age of tho 

 individuals, united by synostosis, i. e. firmly and solidly ankylosed 

 together, without any trace in the adult (and, as a rule, not even 

 in the semiadult) of an inter-premaxillary suture ; this is the case in 

 Lissonycteris (subgenus of liousettus), Fteralopex, and Harpyio- 

 ni/cteris, all of the Bouseitus section, in Hy psiynathus among the 

 lipomophorine Fruit-bats, in Dyacopterus, C'hironn.v, and Ni/ctimene, 

 of the Cynopterus section, and in AJeyaloyhssus, 2Iaeroylossus, 

 Syconycteris, and Xotopteris, among the JIacroylossinee. The 

 opposite extreme is represented by a few genera in which the 

 premaxilloe are not even in contact anteriorly, but distinctly spaced, 

 connected by fibrous tissue only (constantly 'in Eidolon and Boneia ; 

 occasionally in Eonycteris and Mdonycteris). 



3. Infraorbital canal. 



In Insectivora, as well as in primitive Mammalia genenilly, the 

 infraorbital canal is long, its anterior aperture, the infraorbital 

 foramen, situated a considerable distance in front of the orbital 

 cavity. The only forms of Megachiroptera which in the length of 

 the infraorbital canal approach to this primitive condition are the 

 three genera Melonycteris (fig#75, p. 786), Nesonycteris (fig. 76, 

 p. 7U1), and Notopteris (tig. 77, p. 795), all closely interrelated and 

 belonging to the subfamily JIacroylossince. In all other Fruit-bats 

 the canal is considerably shortened, its outer wall, as a rule, a 

 narrow, often sublinear, bridge of bone, and the foramen situated 

 nearly vertically below or only slightly in front of the orbital 

 cavity. 



4. Posiorbital processes and postorbilal foramina. 



Processes. — The postorbital processes are generally small or 

 moderately strong, and if so there is scarcely any trace of corre- 

 sponding lower processes from the zygoma. In a small number of 

 forms, all with heavy dentition (chiefly species of Ftcropus and 

 allied genera), they are stronger than usu'al, reacliing about halfway 

 between frontal and zygoma, and the lower processes are more or 

 less conspicuously developed. Earely (a few large species of 

 Pteropus and Acerodon ; Pteralopcx) they are, at lea.st in aged 

 individuals, so long as to join the lower processes and form a 

 complete ring round the orbit. 



Foramina. — The base of the postorbital process is nearly always 

 pierced by a relatively large foramen (no doubt homologous 

 with the supraorbital notch or foramen of the human skull, for 



