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Show 52 MR. A. H. GARROD ON HALMATURUS LUCTUOSUS. [Feb. 2, 2*2 2*05 that of D. muelleri, the following being the two most important measurements in adult specimens of the same sex (female):- B. luctuosa. B. muelleri. in. in. Length of skull 4*1 4*55 Greatest breadth, from zygoma to zygoma In some minor details there are slight differences. In D. muelleri, as in most species of Macropus, the premaxillary region is bent downwards in such a way that the line formed by the trenchant edges of the molar teeth, if projected onwards to the nose, is quite above the incisor teeth. In D. luctuosa this bending downwards of the snout is not so marked, as will be seen by comparing the side view hi the skull (Plate VII. fig. 3) and the similar one of D. muelleri in Prof. Muller's elaborate work above referred to. The palatine foramina, one large one on each side, together with several much smaller ones behind each, in D. muelleri end behind the transverse palato-maxillary sutures, whilst in D. luctuosa their anterior margins are formed by the palatine plates of the maxillary bones, into which they encroach a short distance. In D. luctuosa the upper of the lacrymal foramina in each lacrymal bone has an ossific ridge behind it, which causes it to be completely exserted, or situated on the face outside the orbit; whilst in D. muelleri the absence of this bony ridge causes it to be situated in a recess on the margin of the orbit. In D. luctuosa the apex of the angular process which is developed downwards from the inferior margin of the maxillary portion of the zygoma, is opposite the anterior cusp of the third molar tooth, whilst in D. mnelleri it corresponds to the posterior cusp of the second molar. With regard to the teeth themselves, the canines in D. muelleri are quite the size of or even slightly larger than the most lateral incisor; in D. luctuosa, however, they are much smaller, being nothing more than slightly curved dentine cylinders about -g^ of an inch iii diameter, as in the subgenus Lagorchestes, and directed downwards and forwards. In both the species the third incisor has an inflection on its labial surface, as in all the species of Macropus: in D. muelleri this fold is a little in front of the middle of the tooth ; and in D. luctuosa it is decidedly nearer the posterior border. In the last-named species there is a similar distinct inflection on the second incisor; in D. muelleri this is not apparent. In D. muelleri the inferior incisor is directed more immediately forward than in D. luctuosa, in which it turns slightly upwards; this peculiarity is correlated with the difference in the obliquity of the premaxillary region (vide Plate IX.). In the enormous premolars there is a slight difference-those of D. muelleri being a little the larger, in the upper jaw having a breadth of 0*55 inch against 0*475 inch for the same teeth in D. luctuosa. In D. muelleri the bony septum between the two fangs of each premolar, especially of the lower jaw, is particularly con- |