344 Transactions of tJie Boyal Society of South Africa. 
whereas the lateral horn of the former is dorsal to the lateral horn of the 
latter. The dorsal surface of the anterior edge of the metasternum has a 
pair of depressions into which the bi-lobed posterior end of the coracoid 
cartilage fits. We have thus a distinct overlapping of cartilages (coracoid 
and metasternum), and both these cartilages are epicoracoidal, since 
Gadow himself says that the sternal apparatus (consequently also the 
metasternum) of Anura belong, phylogenetically to the shoulder girdle and 
not to the ribs. We are thus entitled, I think, to call the pectoral girdle 
of Xenopus laevis arciferous. 
The pelvic girdle is quite similar in shape to that of the frog, but the 
pubes are ossified. It differs from the frog as regards its attachment to the 
axial skeleton, for which see below. The inter-pubic cartilage is pro- 
longed anteriorly into a long, ventral, lobed projection below the rectal 
region. 
The Axial Skeleton. — There are, as in the frog, 9 vertebrae and a 
urostyle ; they may be grouped as follows : 4 pectoral, 4 abdominal, 
1 sacral. Of the pectoral group, the first is without ribs, while the 
succeeding three possess ribs fused with the diapophyses. The ribs of the 
third pectoral vertebra end in small plates of calcified cartilage ; those of 
the fourth vertebra are longer and end in large fiat plates also of calcified 
cartilage. The diapoplyses of the pectoral vertebra are stout and point 
backwards and outwards, while those of the abdominal group are thin, 
sharply pointed, and are directed forwards and outwards. The ninth 
vertebra or sacral is fused with the oss coccygium, but the strong, wing- 
like diapophyses belong to the ninth vertebra alone as is proved by the 
position of the exits of the ninth pair of nerves. 
Gadow calls the vertebrae of the Aglossa epichordal and opisthocoelous. 
For Xenopus laevis, I add (1) neural spines insignificant and (2) the post- 
zygapophyses face downwards and slightly outwards to articulate with the 
prezygapophyses which face upwards and slightly inwards. The articu- 
lating surfaces of the zygapophyses are not plain ; the post-zygapophysis is 
folded into two longitudmal ridges, fitting tightly into two corresponding, 
deep depressions on the prezygapophysis. 
Iliac Articulation. — The anterior ends of the ilia lie along the ventral 
outer edges of the sacral diapophyses, and are firmly attached in that 
position. This is well known, but Gadow does not mention that the 
calcified end-plates of the ribs of the fourth pectoral vertebra curve back- 
wards along the sides of the abdominal group and lie on the anterior, 
dorsal surfaces of the sacral diapophyses. These plates are more or less 
firmly kept in position on the sacrum by connective tissue and elastic 
fibres. 
From the above it will be seen that the Plathander is extremely highly 
developed as far as bi-pedal locomotion is concerned. This sort of move- 
