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Show 1889.] MR. O. THOMAS ON A N E W MUNGOOSE. 623 group. The premolars are all rather longer both vertically and horizontally, and the cusps higher and more distinct. ^, ^ , and m2 are on the whole similar to those of the allied species in their form and relative proportions, but are all markedly larger (compare the dimensions given below with those on p. 78 of my former paper). But it is by the characters of the lower molars that the new species may be most readily recognized. As to size simply, the length of the two molars combined is in H. grandis 17 mm., while in the largest of a considerable series of H. albicaudatus this combined length only attains to 14*4 mm., its ordinary amount being about 13 m m . In structure, as will be seen by Plate LXII. figs. 4 and 5, these teeth in H. grandis are more complicated than in the older known form ; in m1 there is not so much difference, except that the cusps and hollows are more marked, and the ridge running round the posterior half of the tooth, or " talon," is much sharper and better defined. In m2, firstly, the two antero-internal cusps, the paracone and metacone of Mr. Osborn's nomenclature of tooth-cusps1, which have coalesced in H. albicaudatus, are sharply and distinctly separated from one another, so that the primitive anterior triangle forming the blade of the tooth is as well defined as in m1 ; secondly, in the talon, the extra median external cusp characteristic of H. albicaudatus (see p. 76, fig. 1 of the monograph) is duplicated in H. grandis, being supplemented by a second cusp on its internal slope ; then the posterior edge of the talon is more developed, crenulated, and with its centre sharply and prominently notched in the middle line. As a result of this increase in complexity, the size of m2 as compared to m1 is much increased ; for while in H. albicaudatus its length is never more than from 80 to 83 per cent, of that of the latter tooth, in H. grandis the two teeth are of practically the same length, m^ being no less than 96 per cent, as long as m1. In view now of the extreme constancy of the teeth in the present group, both in size and structure, I feel that it would be impossible to refer the Cambridge skeleton to H. albicaudatus, and can only describe it as new, trusting at the same time that its external characters will not. long remain unknown. As will be seen from the figure (Plate LXII. fig. 1), the skull of H. grandis is characterized by its slenderness and by the great length of its facial as compared to its cranial portion. In the skeleton both H. albicaudatus and H. grandis are remarkable for not possessing an entepicondyloid foramen to the humerus, the bony bar usually closing in this foramen being unossified. All other true Mungooses have this foramen closed in by bone, with the exception of the aberrant genera Galidia, Galidictis, and sometimes Suricata. This fact, combined with the addition of a second allied species, gives increased validity to the group " Lchneumia," recognized as a subgenus in m y monograph, but which may possibly in the future have to be admitted as a distinct genus. Dimensions of the type specimen :- Skull. Length (from back of condyle to gnathion) 112 mm.; basal 1 Amer. Nat. 1888, p. 1072. |