b4 
and the Pelicanus Aquilus of Linnzeus, or Man-of-war 
Bird. But the articulations are different in the two 
animals, birds having regularly two, three, four, and 
five phalanges, and the spur, where it exists, supported 
by a single osseous phalanx ; whereas the Otozoum has 
three phalanges in the inner and second toe, four in 
the third and fourth toes. In this last arrangement, 
the Otozoum is decidedly different from all known 
birds. It is not likely to have been a tortoise or 
a lizard. The kangaroo has four feet, and uses 
only two in progression, moving forward by leaps; 
also, like the Otozoum, it has four toes; but the 
size of the toes does not accord with that of the 
Otozoum, nor is the structure of the foot the same, 
so far as we know. It has been suggested by 
Professor Agassiz, that this animal might have been 
a two-footed frog. Nature had, in those days, animal 
forms different from those we are acquainted with ; 
and this might have been the fact with the Otozoum. 
ee 
GROUP SIXTH. 
We have in this group a specimen of the track of a 
four-footed animal, which may have been a frog, though 
different from ours. The feet are unequal in size, and 
present a different number of toes. In existing frogs 
