138 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XIV. 



Dasyuridae and the Didelphiidae it is extremely variable. Various 

 diprotodonts, including most of the macropods and some phalangers 

 have considerable indications of a lambdoid crest and in Phascolarctos it 

 is highly developed. Thylacoleo also is described as having a high crest. 



As to (3), much the same is true of the sagittal as of the lambdoid 

 crest. In the Didelphiidae we find a high sagittal crest in Didelphis and 

 none in the closely related Peramys and Philander. A sagittal crest of 

 some prominence is seen in the skull of Trichosurus. Its presence is less 

 frequent than its absence in both polyprotodonts and diprotodonts and 

 cannot be regarded as of great significance. 



Spencer's characters (i), (2), and (3), therefore, cannot be taken as 

 evidence of the polyprotodont affinity of Wynyardia. 



Characters (5) and (7) seem somewhat correlated and it is evident 

 that in the region of the glenoid fossa and the posterior base of the 

 zygoma we have a more pronounced resemblance to the condition in 

 polyprotodonts than in any living diprotodont with the exception of 

 C&nolestes. In the relatively high position of the glenoid fossa, however, 

 there is approach to the phalangers. It seems, therefore, that only one 

 of the supposed resemblances to polyprotodonts is important and this 

 is approximated in the primitive diprotodont C&nolestes. 



The resemblances to diprotodonts are almost as variable and as 

 difficult to regard as diagnostic, but there are more of them and on the 

 whole they seem more convincing of relationship. This is especially true 

 if comparisons are made only with typical polyprotodonts (as didelphids 

 and dasyurids) and with typical diprotodonts (phalangers), leaving 

 aberrant forms, as Perameles on the one hand and C&nolestes on the 

 other, out of consideration. Thus the large squamosal is found in 

 Phascolarctos much as in Wynyardia completely excluding the alisphe- 

 noid from contact with the parietals; and in general the squamosal tends 

 to forward extension among diprotodonts but, while this offers con- 

 siderable contrast to the condition in the Dasyuridae and Didelphidae, 

 it is fully equalled or even outdone in the Peramelidae. One of the 

 characters suggesting diprotodont relationship of Wynyardia is the 

 large premaxilla but here again the peramelids must be ruled out. The 

 relatively large cranium, the high position of the glenoid fossa, the 

 elevated mandibular condyle, the position and shape of the anterior 

 root of the zygoma, the massive ischium, and the proportionately long 

 hind limbs all seem to point to diprotodont affinity in Wynyardia. 

 Hence, while it may be agreed with Spencer and others that it combines 

 many features of the two groups, it seems best for practical purposes to 

 classify it with the diprotodonts and in recognition of its various unique 

 features to regard it as the type of a distinct family, the WYNYARDIIDAE. 



