369 
Gapvow (15, p. 17), in his recent treatise on the vertebral column, 
concludes that, because GEGENBAUR (17, p. 41) found the epichordal 
type of vertebral development to be associated with the presence of 
a rudimentary tympanic cavity, the development in Xenopus is epi- 
chordal. The argument, however, as Mr. BOULENGER has been good 
enough to point out to me, is not a valid one, for in Hyla, Pelo- 
dytes and Alytes the development is epichordal, and yet these ge- 
nera have a well formed tympanic cavity. But, be the argument sound 
or not, the vertebral development of Xenopus proves on inquiry to 
be strictly and typically epichordal. 
Gapow (15, p. 16—17) says of the Anura that “while in the peri- 
chordal mode the greater share of the formation of the whole vertebra 
falls already to the dorsal cartilaginous elements, the epichordal type 
shows an almost complete suppression of both basiventral and inter- 
ventral elements. ... The suppression ... applies most typically to 
the trunk region, while ‘hypochordal’ cartilage exists in the anterior 
cervical vertebrae, and, above all, in the coceygeum”. This, I believe, 
is a correct summary of our present knowledge of the relations and 
extent of the hypochordal cartilage, and so it is of extreme interest 
to find that in Xenopus there occurs a continuous band of hypo- 
7 
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Fig. 3. Xenopus levis. Larva. (Distance from the snout to cloaca, 30 mm, 
Length of tail, 48 mm. Length of hind limb, extended, 30 mm. Fore limb, extended, 
9 mm.) Vertebral column, ventral view. 
Fig. 4. The same, seen from the left side. d’. articular surface for the second rib, 
he, band of hypochordal cartilage, Other letters as before, 
