A NEW GENUS OF FOSSIL MAESUPIALS.— LONGMAN. 75 



complex premolar on the right side of ^Macleay's " Zygomaturus trilobus" was 

 an abnormality or was incorrectly associated with the cranium. Scott (1915, 

 p. 10) also quotes a remark from him which shows that Lydekker did not 

 consider this oval tooth as characteristic of Nototherium. But Scott's illus- 

 trations and descriptions show that this large tooth is associated with the 

 specimen described by him as NototJieriiun tasmanicum and with ^Y. mitchelli. 

 Glauert (1912) also figured (Plate VI, fig. 10) a West Australian tooth of a 

 somewhat similar character. Amongst our specimens are three loose teeth of 

 this type and an additional one is in situ in a maxilla with the rest of the molar 

 series. It should also be noted that one of the teeth figured as the type of 

 Prochocrns celer by De Vis is of interest here, as pointed out by the writer when 

 dealing with this material (Longman, 1916, p. 86). 



In response to my request, ]\Ir. Charles Hedley, Australian Museum, has 

 kindly forwarded a note on the premolars of Macleay's "Zygomaturus trilobus," 

 as observed by ]\Iessrs. Thorpe & Troughton, of the INIuseum staff. This states 

 that both teeth are firmly in situ, the right one being nearly complete, but that 

 "on the left side is badly fractured." 



This clearly shows that the large oval premolar is not an abnormality, 

 but a definite characteristic of Macleay's "Zygomaturus trilobus." It certainly 

 follows that (dl crania ivitli triangular premolars are generically disfinct. 



Although Nototherium inermc, fi.rst described by Owen (1845, p. 231) as 

 indicating a distinct genus "by a total absence of incisors," has page precedence 

 ( a single page ! ) over N. mitchelli, the rules of international zoological nomen- 

 clature give latitude for the selection of the second species as the type. 

 Nototherium mitchelli is certainly the "best described, or best figured, or best 

 known" of the three species recorded by Owen from mandibular types. 

 Notwithstanding the discrepancies between the views of Owen, Lydekker, and 

 De Vis as to the premolars of Nototherium, Lydekker 's action in taking 

 N. mitchelli as the typical species should be confirmed, and that species is 

 hereby selected as the type of Nototherium, sensu stricto. The cranium described 

 by Macleay thus becomes a heautotype, and Simoprosohus De Vis (1907) is a 

 synonym. A second species is N. tasmanicum, the subject of Scott's excellent 

 monograph (1915). 



Apart from Euowenia, there are two other kinds of Nototherian crania 

 with subtriangular premolars. In one, typified by N. victorice^, the zygomatic 

 arches are relatively normal, and judging from fragments in the Queensland 

 ]\Iuseum these crania may require a distinct generic name when better known. 



Euryzygoma represents the third section. In this genus the zygomatic 

 arches reach anteriorly the remarkable development recorded in this paper, 

 and the anterior zygoma root is deeply recessed under a horizontal infraorbital 

 platform. 



