IOI4 General Notes. [October, 
That the digits of the Cetacea develop as part of the continu- 
ous blastema of the embryonic appendicular skeleton as in other 
vertebrated animals, there can be no doubt. That the joints and 
segments of their limbs also become gradually defined in serial 
order from the shoulder and hip girdles outward, also admits of 
no doubt, as may be seen upon studying sections of the manus, 
a quarter inch in length, of a foetal Globiocephalus two inches in 
total length. In like manner there can be no doubt of the fact 
that the cartilaginous extensions of the ungual phalanges of pin- 
nipeds are a part of the original blastema from which the ossified 
portions of the skeleton of the limbs of these animals has de- 
veloped. 
In man ,the shafts of the three phalangeal segments of the 
digits of the manus ossify almost contemporaneously. In Globio- 
cephalus, on the other hand, in a specimen one-third grown, it is 
found that the proximal segments of the second and third digits 
ossify apparently at about the same time as their isomeres in the 
first, fourth and fifth digits, whereas the distal or extra peripheral 
segments develop ossific centers enchrondrally much later. These 
development and ossification of the extra terminal digits of the 
existing whales. In fact, in some of the existing seals these car- 
tilaginous prolongations of the ungual phalanges are long enough 
in the pes to afford the basis for three new and additional seg- 
_ ments to each digit, as long as the three normally developed in 
each toe. . 
__ The proof that the extra terminal segments of the digits of 
he cetacean manus have been added distally, is the fact that the 
structure of the carpus is not, in any essential feature, different 
ure from that of other mammals so far as the presence or 
b 
