166 Zoological Society :— 
Shield Reptiles in the British Museum,’ I stated that all the spe- 
cies there noticed ‘‘ perhaps may prove only to be varieties of the 
same species, or dependent on age”’ (p. 52). 
A larger series of specimens from the same locality has shown 
that such characters as the shape and thickness of the shields, and 
especially of the first vertebral shield, which have been hitherto to 
some extent depended on for the separation of the species, are very 
variable. Therefore the discovery of some other more permanent 
characters seems important; and the form and disposition of the 
shields on the head appear to furnish such characters. 
Mr. Cope observes that 8. Derbianus differs from S. sinuatus of 
Smith ‘‘ mainly in the form of the upper mandible, which is ob- 
tusely hooked in the former, bidentate in the latter.” I suspect he 
must have been misled in these observations by figures or descriptions ; 
for the jaws of the typical specimens of the two species are very similar. 
It will be necessary to separate the genus into three sections, ac- 
cording to the form of the head, premising that I only know the 
species belonging to the third section from the descriptions of MM. 
Duméril and Bibron, as all the specimens that have come under my 
observation belong to the first or second section. These sections 
may be thus characterized :— 
I. Head short and broad; the upper jaw obscurely notched and 
bidentate in front ; the crown shielded to a line even with the 
back of the tympanum. 'Tanoa. 
1. STERNOTHZRUS SINUATUS, A, Smith, S. African Zool. t. 
Head rather broad, depressed; jaws pale; the temporal plate 
Head of S. sinuwatus. 
broad and short, only reaching to the front of the tympanum, and 
with another rather smaller similar plate behind it over the ear; the 
hinder vertebral plate of the adult as wide as long, not tubercular ; 
the fore legs with small scales, and with some very wide, slender, 
band-like shields on the inner side of the upper surface; the ster- 
num with a narrow deep notch behind. 
Sternotherus castaneus, part.; Gray, Cat. Shield Rept. B.M. p.52. 
Hab. S. Africa: Natal (Dr. Krauss). “ 
_— ee ee 
