Zoologij.l NATURAL HISTORY OF VICTORIA. [Reptiles. 



Altliougli popularly called the Murray Turtle by the colonists, 

 the structure of the feet is that proper to the walking Tortoises, 

 and not the exclusively swimming paddles of the true Turtles. 



This species varies very much in the rugosity of the upper 

 plates and in the depth 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 convex, thicker and more rugose, 

 than the females, and with larger tails. The young are more 

 nearly orlDicular, and with the notches in the posterior marginal plates 

 very much deeper and more conspicuous than in the adults, and 

 with, of course, the shields covering the shell very much thinner. 

 The above series of measurements of specimens shows that the 

 proportion of length to width of the vertebral plates also varies 

 greatly in specimens otherwise perfectly alike, the 4tli vertebral 

 plate being sometimes as long as wide, and sometimes nearly twice 

 as wide as long. The upper surface of the carapace is uniformly of a 

 very dark-brownish or blackish-olive ; the marbling with grey which 

 is mentioned by older writers only appearing in dried specimens ; the 

 under-side of the sternum is always of a nearly uniform yellow- 

 ochre tint, becoming of a more greenish or brownish hue towards 

 the marginal plates, 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 con- 

 sideralDly also, irrespective of other characters. The so-called 

 beards or barbels are two minute, soft, retractile, conical tubercles 

 or papillae, very likely to be overlooked, as when retracted they 

 only leave a smooth oval spot. The 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 

 fi'om the South American Platemys and Hydraspis^ the two barbels 

 under the chin being really present in all the specimens if carefully 

 looked for, and the slightly more distinct plating of the temples 



C 13 ] 



