MIR .-RIBEIRO — CERATOPHRYS AND STOMBUS 213 
The tadpole in its simplest stage is formed as in Plate II, fig. I, and measures 
about 25 millimetres, is of olivaceous colour marbled with a lighter shade 
and with a purplish blue which becomes very bright after death. The mouth 
is the same as presented in next stage as shown in figs. 2a and 2b, presenting 
two ranges of parallel denticules on the upper lip and 3 on the lower up to 
the psittaciform beak and internally. When the limbs grow and emerge 
(figures 2 and 2a), the joints are provided with balls or adhesive discs, pre- 
sent both on fore and hindfeet, which is verified as soon as they emerge 
from the brachial cavity. These dises and the natatory membrane between 
the finger joints, remain during ulterior evolution, as seen in figs. 3 and 
ha. Here the hyloid aspect of the tadpole is very marked, although at the 
base of the first joint can be seen the excavating shovel of Stombus. Also 
the marking of arrowhead form, drawn by the cutaneous folding which 
runs from the eyes to the base of the tail, gives the conviction of identity. 
This figure is already as shown in fig 3. In this stage and in the preceding 
the interdigital membrane of the forefeet is imperceptible owing to transpa- 
rency, but in stage of fig 4 it is very apparent as also the whole system of 
articular callosities as verified in fig. 4 a. The colouring begins to be de- 
fined from fig. 2 and accentuates up to h, when it gives a vague idea of 
Hyla radiana. In 5, finally, no room is left for doubt as to the definite 
animal. The capital points of this evolution arise from the disparity in stages 
anterior to fig. 5 from the definite stage which this figure indicates. And the 
absolute divergence of these stages as to those observed referend to the tad- 
poles of Ceratophrys dorsata. 
These facts prove not only that Stombus and Ceralophrys are two com- 
pletely distinct genera, as also, that the similiarity of the two definite forms 
is the result of a parallelism identical to that observed between these two ge- 
nera and Ceratobatrachus of Australia. | 
The immediate conclusion to which we are led is that Stombus pro- 
ceeds from the Hyla branch whereas Ceratophrys derives from Rana — or 
what is equivalent — that we are still far from an effective natural classifi- 
cation when we come to consider those that are up to this day known. 
