the upper incisors are never less than three, and may be as many as five in the upper jaw and six in the lower. The canines are trenchant. There is no caecum.
Fig. 77.—Front view of skull of Koala (Phascolarctos cinereus), illustrating Diprotodont and herbivorous dentition. (From Flower.)
Fig. 78.—Longitudinal section of the skull of the Thylacine (Thylacinus cynocephalus). × ½. a, Angular process of mandible; AS, alisphenoid; BO, basioccipital; BS, basisphenoid; cd, condyle of mandible; ET, ethmoturbinal; Ex.O, exoccipital; Fr, frontal; ME, ossified portion of mesethmoid; MT, maxilloturbinal; Mx, maxilla; Na, nasal; OS, orbitosphenoid; Pa, parietal; Per, periotic; Pl, palatine; PMx, premaxilla; PS, presphenoid; Pt, pterygoid; SO, supraoccipital; Sq, squamosal; Vo, vomer. (From Flower's Osteology.)
The genus Thylacinus contains but a single species, which is now limited to Tasmania, and is generally known as the Tasmanian Wolf. It has the build of an ordinary Wolf, and is of about the same size. The hinder part of the body is marked with a series of black transverse bands. The hallux is entirely wanting; the pouch opens backwards. The marsupial bones are minute and unossified. The dental formula is I 4/3 C 1/1 Pm 3/3 M 4/4 = 46. There are four mammae. This animal, now confined to Tasmania,
