The alternate interlocking of the crowns of the teeth of the upper and lower jaws, which is their general relative position in the Carnivora, is well marked in regard to the premolars of the Viverridce (fig. 580, IV.): as the lower canine is in front of the upper, so the first lower premolar rises into the space between the upper canine and first upper premolar ; the fourth lower premolar in like manner fills the space between the third upper premolar (p. 3) and the sectorial tooth (p. 4), playing upon the anterior lobe of the blade of that tooth which indicates by its position, as by its mode of succession, that it is the fourth premolar of the upper jaw. The first true molar below, modified as usual in the Car nivore to form the lower sectorial, sends the three tubercles of its anterior part to fill the space between the sectorial (p. 4) and the first true molar (m. 1) above. In the Mu sangs the lower sectorial is in more direct opposition to its true homotype, the first tubercular molar in the upper jaw ; and these Indian Viverridce (Paradoxuri) are the least carnivorous of their family, their chief food consisting of the fruit of palm-trees, whence they have been called " Palm-cats." _Mycelia. —The dentition of this genus pre sents a nearer approach to the strictly car nivorous type by the reduction of the tuber cular molars to a single minute tooth on each side of the upper jaw, the inferior molars being all conical or sectorial teeth : the molar teeth in both jaws are larger and stronger, and the canines smaller in proportion than in the Feline species, from the formula of which the dentition of the hywna differs numerically only in the retention of an additional pre molar tooth, p. 1 above and p. 2 below, on each side of both jaws. The dental 3-3 formula of the genus Hyena is in.
3-3' 1-1 4-4 1-1 c. pm. vi. = 34. The crowns of the incisors form almost a straight tranverse line in both jaws, the exterior ones, above, being much larger than the four middle ones, and extending their long and thick inserted base further back : the crown of the upper and outer incisor (i. 3.) is strong, conical, recurved, like that of a small canine, with an anterior and posterior edge, and a slight ridge along the inner side of the base. The four intermediate small incisors have their crown divided by a trans verse cleft into a strong anterior, conical lobe, and a posterior ridge, which is notched ver tically; giving the crown the figure of a trefoil. The lower incisors gradually increase in size from the first to the third ; this and the second have the crown indented ex ternally ; but they have not the posterior notched ridge like the small upper incisors ; the apex of their conical crown fits into the interspace of the three lobes of the incisor above. The canines have a smooth convex exterior surface, divided by an anterior and posterior edge from a less convex inner side : this surface is almost flat and of less relative extent in the inferior canines. The first
premolar above (p. I) is very small, with a low, thick, conical crown : the second presents a sudden increase of size, and an addition of a posterior and internal basal ridge to the strong cone. The third premolar exhibits the same form on a still larger scale, and is remarkable for its great strength. The pos terior part of the cone of each of these premolars is traversed by a longitudinal ridge. The fourth premolar is the carnassial tooth, and has its long blade divided by two notches into three lobes, the first a small thick cone, the second a long and compressed cone, the third a horizontal sinuous trenchant plate : a strong triedral tubercle is developed from the inner side of the base of the anterior part of the crown. The single true molar of the upper jaw (ni. 1) is a tubercular tooth of small size : transversely oblong in the Hyarma vulgaris and H.fusca ; smaller and sub•cir cular in the Hyena crocuta ; still smaller and implanted by a single fang in the Hycena spelcra : in all the existing species of Hymna it has two fangs. The first premolar of the lower jaw (p. 2) fits into the interspace between the first and second premolars above, and answers, therefore, to the second lower premolar in the Viverridce: it is accordingly much larger than the first (p. 1) above ; it has a ridge in the fore-part of its cone, and a broad basal talon behind. The second (p. 3) is the largest of the lower premolars, has an anterior and a posterior basal ridge, with a vertical ridge ascending upon the fore as well as the back part of the strong rounded cone : the third premolar (p. 4.) is proportionably less in the Hycena crocuta than in the H. vulgaris: its posterior ridge is developed into a sm .11 cone; the last tooth (m. 1) is the sectorial, and consists almost entirely of a blade divided by a vertical fissure into two sub-equal com pressed pointed lobes : the points are less produced than in the Felines, but the lower sectorial of the hymna is better distinguished by the small posterior basal talon, from which a ridge is continued along the inner side of the base, and is slightly thickened at the fore-part of the crown. According to the relative po sition of the crowns of the premolars the third below ought to be the last, being analogous to the fourth in the Virocrrida, and the sec torial should be first true molar : we shall find this view confirmed by the test of the mode of succession of the permanent teeth. But the mode of implantation of the premolar and molar teeth may first be noticed. The first upper premolar has but one fang; the second and third have each two ; the sectorial tooth has three, the two anterior ones on the same tranverse line, the inner one supporting the tubercle. The lower premolars and sectorial have each two flings, there being none truly answering to the first above : the anterior root of the lower (p. 1) sectorial tooth is very strongly developed in the great extinct Cave-Hymn a.