439 



it approximately on the grounds previously defined. If, however, a narrow vacuity with 

 a rounded concave hind border in the bony palate be structural, it would represent, in 

 the fossil, the right incisive foramen, and would indicate a shorter diastema and inter- 

 vening bony palate than I have estimated ; I incline, however, to view such vacuity as 

 accidental, and to place the incisive foramina as in the outline to Plate LXXIX. 

 Further acquisitions of the cranial parts of Macropus Titan may be hoped for to deter- 

 mine this part in the restoration of that fine extinct species. 



Subjoined are admeasurements of the fossil skull above described, with corresponding 

 ones of the skull of a mature male Macropus major. 



Macropus Macropus 

 major. Titan. 

 in. lines. in. lines. 



Length of skull from superoccipital ridge to fore part of d * . 4 9 6 6 



Breadth of skull at widest span of zygomata 4 3 5 9 



Breadth of cranium at postorbital constriction 10 16 



Breadth of cranium at the mastoids 211 38 



Breadth of foramen magnum 010 Oil 



Length of cranium from superoccipital ridge to postorbital 



constriction 27 32 



Length of cranium from superoccipital ridge to fore border of 



orbit 4 3 5 8 



Length of orbito-temporal vacuity, lower opening .... 1 9 26 



Breadth of orbito-temporal vacuity, lower opening ... 1 4 18 



From hind border of palate to fore border of d * .... 2 4 3 



Breadth of palate between the right and left molars (m 2) . 1 4 110 



From alveolus of m 3 to hind border of palate 6 11 



From lower border of orbit to alveolar border at m 1 ... 1 16 



Length of series of four molars (d * to m 3) 1 10 2 2 



Length of m 2 and m 3 11 13 



Breadth of fore lobe of m 3 4£ 6 



§ 15. Sthenurus Atlas (fore part of skull, with incisors and milk-molar dentition). — 

 Confirmation of the ascription of the second type of upper third incisor to an extinct 

 species of Kangaroo with a large premolar tooth, has been had by the reception of a 

 specimen of that part of the skull and dental system which, as a rule, is wanting in 

 cranial fossils of these extinct Marsupialia. 



This specimen consists of the facial part of the skull, including the anterior halves of 

 the orbits to the ends of the premaxillaries, with their incisor teeth (Plate LXXVI. 

 fig. 2). The molar dentition is represented by an anterior tooth of trenchant character, 

 followed by three double-ridged molars on the left (ib. ib. d 3, d 4, m 1) and two on the 

 right side (Plate LXXVII. fig. 4, d 3, d «). The third on the left is emerging from its 

 socket with the ridged summits of the lobes narrow ; a portion of a formative cavity of 



