348 PEOPESSOE OWEN ON THE SPECIES OF PHASCOLOMTS. 



In an old male Tasmanian Wombat their basal breadth equals three fourths of their 

 length (PI. LI. fig. 4)'. The outer angles of the base are divided from the lacrymal 

 tubercle (73) by a fronto-maxiilary suture (11-21) 3 lines in breadth. The sides of the 

 pair of nasals converge forward at the hinder third, then run parallel, gently curving 

 inward, and finally run to the margin of the nostril, with a slight curve outward. Thus 

 the course of each lateral border of the nasals is undulate. Their tips extend forward 

 about 3 lines in advance of the naso-premaxillary suture (13-22), and are bevelled ofi' 

 to an obtuse point from veithout obliquely inward and forward. Together they form the 

 middle third of the upper border of the bony nostril. The frontals (ib. ii) make a slight 

 projection into the middle of the fronto-nasal suture (ii-ia), which from this shallow 

 indent runs outward and a little forward to the nasal process of the maxillary (21). The 

 naso-maxillary suture (15-21) forms the hind fifth part of the lateral border of the nasals ; 

 the naso-premaxillary suture (15-22) runs along the rest of the extent of the nasal bones, 

 i. e. to the beginning of their free ends, which are short and subobtuse. 



In a second Wombat the nasals differ in their breadth being equal to three foui'ths 

 of their length, or as 75 to 100, in the absence of any median indent of the fronto-nasal 

 suture, and in the sharper convergence of the hinder fourth pai't of the lateral margins. 

 These margins describe a similar wavy course, convex outward along the middle, or a 

 little in advance of it. The apices overhanging the nostril are sharper and more pro- 

 minent than in the last specimen. 



In a third, somewhat younger Phascolomys vombatus (PI. LI. fig. 8), the lateral 

 margins converge more gradually, and in an almost straight line from the base to the 

 anterior fourth of the nasals, where the margins extend nearly straight to the nostril. 

 The middle sixth part of the fronto-nasal suture (11-15) is nearly straight or transverse ; 

 the rest extends outward and more obliquely forward than in the two preceding spe- 

 cimens. The fronto-maxiilary suture (n-21) is 4 lines in extent. The nasal apices 

 projecting beyond the premaxUlo-nasal sutures are sharp and form one fifth the length 

 of the whole lateral margin. The basal breadth bears a greater proportion to the 

 length of the nasals than in the first-cited skull. 



Phascolomys platyrMnus (PI. LI. fig. 1), in the shortness of the naso-maxillary suture 

 (ib. 15-21) and the deep emargination of the fore part of the nasal process of the pre- 

 maxUlary (ib. 22), is more nearly allied to Phascolomys vombatus than either of these are 

 to Phascolomys latifrons^. But the nasal bones of Phascolomys platyrMnus are relatively 

 broader than in Phascolomys vombatus ; the outer basal angles approach nearer to the 



' This proportion is expressed as follows by Dr. Murie in describing his specimen of Phascolomys vombatus. 

 " The proportional breadth of the two nasal bones at their hinder ends is to their length, 68 to 100." — 

 Proc. Zool. Soc. June 27, 1867, p. 802. 



' This relation is well pointed out by Dr. Murie, who remarks that " Phascolomys latifrmis shears off from 

 the common form of Wombat, and reverts to the true marsupial type in several particulars." — Loc. cit. p. 800. 

 He does not, however, exemplify his ideal type : the postorbital processes are almost peculiar to Ph. latifrons 

 among Marsupials. 



