25 



In Decade IX. of his Prodromus of the Zoologn of Victoria, Sir Frederick McCoy 



writes : — 



This species varies nmcli in the rugosity of the upper plates and in the deptli of the shell, some of the same age and 

 sex being much smoother and flatter than others. The males usually are narrower and deeper or more c mvex, thicker and 

 more rugose than the females, and with larger tails. The young are more nearly orbicular, and with tlie notches in tlie 



SKELETON OF TURTLE. 



posterior marginal plates very much deeper and more con- 

 spicuous than in the adults, and with, of course, the shields 

 covering the shell very much thinner. A series of measure- 

 ments also shows that the proportion of length to wiilth of 

 the vertebral plates also varies greatly in specimens otherwise 

 perfectly alike, the fourth vertebral plate being sometimes 

 as long as wide, and sometimes nearly twice as long. The 

 upper surface of the carapace is imiformly of a very dark- 

 brownish or blackish olive ; the marbling with grey which is 

 mentioned by older writers only appearing in dried specimens ; 

 the underside of the sternum is always of a nearly uniform 

 yellow ochre tint, becoming of a more greenisli or brownish hue 

 towards the marginal places, but without dark margins or 

 spots ; the skin is uniform blackish, except the edges of the 

 jaws and the streak from them along the sides of the neck 

 and touching the lower edge of the ear drum which is 

 yellow. 



The size of the granules on the skin of the neck varies 

 considerably also irrespective of other characters. The so- 



calleil beard or barbels arc two minute, soft, retractile, conical tubercles or papilla;, very likely to be overlooked, as 

 when retracted they only leave a smootli oval spot. Tile presence or absence of this so-called beard cannot be taken as 

 a character of generic value with advantage, as it varies so much like the other appendages of the skin. 



These mud tortoises can scarcely be said to differ generically from the South .American Platemys and Hydraspis, the 

 two barbels under the chin being really present in all tlie specimens if carefully looked for, and the slightly more distinct 

 plating of the temples with small polygonal shields constituting a very slight ground for generic distinction. The eggs 

 have a strong white calcareous shell of a slightly ovate form, very little wider at one end than the other, bluntly rounded 

 at each end. 



I'JIEFAKED srEOIiME.X SHOWING INT-EKNAl, OKG.VNIS.M OF 

 MUD TURTLE. 



