. Elementary text-book of zoology. MAMMALIA. 525 Keeping these points in mind, we may glance at the anatomy of the two types. Placing the two skulls before us, we note their features in common as follows:—In each the incisor teeth are small and pointed and are never more than §, a distinc- tion from Polyprotodontia; the canines are long, powerful and pointed; and the premolars and molars have sharp- edged cusps, with an absence of the flat grinding -surfaces seen in the herbivorous types. In both there is a specially large cusped tooth in upper and lower jaw which is called the "carnassia
. Elementary text-book of zoology. MAMMALIA. 525 Keeping these points in mind, we may glance at the anatomy of the two types. Placing the two skulls before us, we note their features in common as follows:—In each the incisor teeth are small and pointed and are never more than §, a distinc- tion from Polyprotodontia; the canines are long, powerful and pointed; and the premolars and molars have sharp- edged cusps, with an absence of the flat grinding -surfaces seen in the herbivorous types. In both there is a specially large cusped tooth in upper and lower jaw which is called the "carnassial" tooth, usually said to be used for breaking slippery bones. The. glenoid cavity of the squamosal is a Fig. 362.—Lateral View of Lion's Skull x \. {Ad nat.). j Zygomatic Arih. \ Auditory Bulla. Carnassial Tooth. ETT^Postglenoid Process. transverse groove, and into this there fits the cylindrical condyle of the mandible. Owing to this arrangement the mandible can only move in a perpendicular plane. Imme- diately behind the glenoid cavity is a wide process of the squamosal, called the postglenoid process, which prevents all backward horizontal motion of the mandible. On the cranial surface there are at least two large bony crests—the sagittal crest along the middle dorsal line and the occipital crest from side to side at the junction of parietals and occipitals. These form the surfaces of origin for the large jaw-muscles [temporalis) which pass down in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Masterman, Arthur Thomas. Edinburgh, E. & S. Livingstone
Size: 2308px × 1082px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1900, bookyear1902
