1910.] Rcscmhhnicc.'^ hdireen Chrysochloins and Notorycta^. 257 



the maxillary (Leclio). Instead of the condition of the zygomatic arch 

 being an indication of affinity to the Monotremes, as held by Leche (p. 141) it 

 may rather be due to the derivation of Chrysochloris from some Zalambdo- 

 dont which had already lost the malar, but which later evolved a new 

 zygomatic arch out of the zygomatic process of the maxillary, which grew 

 backward until it touched the zygomatic process of the squamosal. Here 

 then would lie a deep seated difference from the Notorydes skvdl. 



In Notorydes the cranial sutures tend to remain open (Stirling, 1891) 

 as in ISIarsupials, but in Chrysochloris as in Insectivora they are obliterated 

 even in the very young skull. 



The conditions in the auditory region in Notorydes and Chrysochloris 

 are radically different. A comparison of specimens of Chrysochloris aurea 

 and Notorydes typhlops in the American Museum shows that in Notorydes 

 the conditions are directly comparable with those in the smaller Dasyurids 

 such as Antechinomys and Phascocologale, i. e., there is a very large "ali- 

 sphenoid bulla," which conjoins posteriorly with an ex])ansion of the petrosal, 

 the entotympanic (p. 240), while the true tympanic takes no part in bound- 

 ing the tympanic cavity, but lies in the postero-external border of the 

 ali'sphenoid bulla (r/. also van Kampen, 1905, p. 404). In Chrysochloris 

 on the contrary the conditions in this region are rightly described by Leche 

 (1907, p. 73) as "ein Differenzierungsprodukt des Verhaltens bei Centetidse 

 und zwar zunachst der ursprlmglichsten Formen dieser Familie, der Oryzoric- 

 tina?." As in Microgalc (Fig. 13, B), the tympanic processes of the ali- and 

 basisphenoid form a rim which in Chrysochloris is semicircular and em- 

 braces the periphery of the expanded hemispherical tympanic. No better 

 example could be cited, of the iniportance of the auditory region in the study 

 of ordinal relationships, and of "pak^otelic" characters of this kind as com- 

 pared with "csenotelic" or adaptive resemblances. 



The proximal ends of the nasals of Notorydes spread widely, as in Marsu- 

 pials. In Chrysochloris, owing to the absence of sutures it cannot be affirmed 

 positively that the nasals do not spread proximally, but in the top view of the 

 skull the nasal region compares so closely with that in the Centetoidca that 

 there seems little reason to doubt that the nasals ended proximally in a 

 median V and likewise very early coalesced. The Chrysochloris skull also 

 shows the tubular form of the fronto-parietal region which is so characteristic 

 of the Centetoids. 



The jaw of Notorydes has a typically inflected angle, a sliarp external 

 masseteric ridge, and a pterygoid fossa, as in Marsupials, whereas the char- 

 acters of the Chrysochloris jaw may readily be derived from those of the 

 Microgale type. 



(2) Manv of the similarities in the skeleton are associated with differ- 



