1900.] FOSSIL MARSUPIAL FROM TASMANIA. 779 



which meet the nasals and prevent the maxillae from coining into 

 contact with the frontals, (6) the great width of the nasals, (7) the 

 very anterior position of the infraorbital foramen, and (8) the 

 general massiveness. 



Owing to the base of the skull being broken, the length measure- 

 ment from the basion to the gnathion cannot be taken, and 

 therefore, for the purpose of comparison with other skulls, the 

 total length from the posterior end of the sagittal crest to the 

 anterior end of the nasals, that is the total length along the mid- 

 dorsal line, is taken. Though this is not so satisfactory as the former 

 measurement, still it will serve to a certain extent as a basis of 

 comparison. 



The total length is just 100 mm., and the greatest width across 

 the zygomata is 67 mm. Taking the same length of various 

 species of marsupials, measured for comparison, as 100, we find 

 that the proportionate breadth is as follows : — Trichosurus fuligi- 

 nosus 58*7, T. vidpecula53'7, Pseudochirus herbertensis 60, P. archeri 

 63'8, P. coohi 53'7, Phascolarctos cine reus 59, Cuscus sp. 59, 

 Bettongiapcnicillata 56*3, Dendrolag us bennettianus 55 - 7 ', Phascolomys 

 mitcJielli 75*2, Dasyurus maculatus 68'2, Sarcophilus ursinns 77, 

 Dideljihys sp. 56-9. In regard to this it is intermediate between 

 such extreme forms as Sarcopliilus on the one hand and Petrogalc 

 on the other, and approaches most nearly to Dasyurus, showing a 

 decidedly greater width than is met with in the Phalaugeridse. 



The occipital region is separated from the upper surface of the 

 skull by a well-marked lambdoidal crista which curves somewhat 

 backward, so as to afford a concave surface for the muscles of the 

 neck, the occipital plane sloping slightly downwards and forwards 

 and not being vertical as in most marsupials. The curvature of 

 the ridge is carried to about the same extent as it is in Dasyurus, 

 the ridge of either side curving slightly towards the middle line. 



From a point just behind the intertemporal constriction a 

 strongly marked sagittal crest runs backwards to the lambdoidal 

 crista, the former being as well developed as in Tliylacinus and 

 Dasyurus, In this respect the fossil offers a strong contrast to 

 the Phalangerida?, in which the two temporal ridges run backwards 

 converging towards the lambdoidal crista ; so that no such sagittal 

 crest is formed as is characteristic of the Dasyuridse, and is seen 

 also in Didelphys marswpialis. On the upper surface of the frontals 

 there is a shallow, but sharply outlined, depression, the converging 

 margins of which are continuous posteriorly with the sagittal crest. 

 The parietal suture extends about as far forwards as the latter. 



A very remarkable feature is the great extent and anterior 

 extension of the squamosals, the anterior ends of which reach 

 almost as far forwards as those of the parietals. An equally 

 striking feature, and one in which the fossil agrees with Dasyurus 

 and Sarcophilus, is the general parallelism of the upper part of the 

 suture of the squamosal with the sagittal crest. In such forms as 

 the Phalangerida) for example the sutures show a continuous 

 marked convergence towards the middle line posteriorly. In regard 



