) 
(8) The monotreme-marsupial linc have developed a number of toramina 
in their own special way. 
(4) The Rodentia have chiefly developed those of the inferior part of the 
squamosal bone, if any. 
(5) The Carnivora commenced with but few foramina, and have obliter- 
ated these on attaining their highest development. 
(6) The history of the Quadrumana is identical with that of the Car- 
nivora. 
(7) The Perissodactyla present very few foramina in the lowest forms, 
“and did not increase them in the line of the Rhkinoceride. In the line of 
the horses an increase in their number appeared early in. geologic time, 
and is fully maintained in the existing species. 
(8) In the Omnivorous division of the Artéodactyla, time has obliterated 
all the sinous foramina. In the Camels an increased number was apparent 
at the same geologic period as in the history of the horses (White River or 
Lowest Miocene), and has been maintained ever since ; while the existing 
Pecora present a larger number of the foramina than any of the class of 
Mammalia. 
The only relation between these structures and the habits of the species 
concerned that can now be traced is, that the largest number of the foram- 
ina is found in the specialized vegetable feeders, while the smallest num- 
ber is found in omnivorous forms. : 
I now give a synopsis of the distribution of the sinous foramina accord- 
ing to the foramina themselves. The f. f. déploética, posteygomatica and 
supratympanicum are not included, as their existence is restricted to the 
_few types already mentioned. 
I. No foramina. 
Homo, Troglodytes, Cynocephalus, Semnopithecus, Mycetes, Cal- 
lithria, Ateles. 
Uncia, Hyena, Arctocephalus, Trichecus. 
Elephas, Hyraz ; 
Sus, Phacocherus, Dicotyles. 
Lepus, Lugidium, Cercolabes. 
Cholepus, Bradypus. 
IL. Postglenoid only. 
a. Rudimental. 
Felis ; Phoca. 
aa. Developed. 
Chlamydophorus. 
Lemur, Chirogaleus, Tarsius ¢ 
Macacus. 
Mustela, Putorius, Mephitis ; Canis. Vulpes, Urocyon, Viverra. 
Procyon, Nasua, Bassaris. 
Tragulus. 
aaa. Knormous. 
Lagostomus and Geomys. 
