10 



Records of the S.A. Museum 



In most cases the characters imhcatecl can l)c ascertained only hy careful 

 examination with the aid of a magnifying glass. The numher of rows of scales 

 round the body is very constant in Australian species, and forms a reliable 

 secondary division under each main STroup; the range in the number of row-- 

 varies from 1 8 to 24, and they are, normally, always in an even series. Examples 

 are \ery occasionally found wherein this is departed from ; in such, however, it 

 will be found that some of the scales in one or more rows have been split, fused 

 with others, or that some other abnormality exists ; the scales bordering the head 

 shields are rather subject to such irregularities. 



Specific characters. The lateral contnur of the head, as \iewed from 

 above, is usuallv rounded, but it may be blunt as in T. brooiui, sub-acute as in 

 T. batillns. or markedly trilobed, a condition found only in T. hitiihcrciilatus. 

 The profile is also generally rounded, but provides varying degrees of angularity, 

 T. kenti furnishing the extreme instance, in which species the snout is actitely 

 angular; in T. grypus the snout forms a distinct hook, like the beak of a cockatoo. 



Ciiart 4. Distribution of • T. torresiuiiiis, O T. <livcrsiis, 1 T. affiiiis 



