108 B. G. Wilder on a foetal Manatee and Cetacean. 
The most recent writer concludes an able anatomical descrip- 
tion of the manatee with a diagram, in which equal weight 
seems given to the cetacean and ungulate relations of the 
Sirenia (Murie 1, 190 
r. Murie continues as follows: “Is it (the manatee) a retro- 
antedated swarms of mammals of intermediate organization 
which would fill up the chasms of structural differentiation, 
a further profound investigation into the principles of the doc- 
trine of evolution.” 
t will be noted that, although Dr. Murie uses the word retro- 
grade in his general query respecting the affinities, the idea is 
not distinctly enunciated. For while embryo Pachyderms and 
etacea are mentioned as likely to throw light upon the 
problem, those of Sirenia are not alluded to. This is not so 
strange in view of the fact that the smallest foetus then known 
(Daubenton, 22) was about ten inches long (-254) and already 
unmistakably a manatee. 
A fjinities of the Sirenva.—The likeness of the foetal manatee’s 
limbs which, in the adult forms, seem to separate the Sirenia 
from the Ungulata and to unite them with the Cetacea. “In 
are 
five ; the latter, relatively positive. 
An the case of the manatee the large tail, the absence of 
hinder limbs, the pinniform manus, the flexion of the head 
upon the chest, and the absence of external ear; these charac- 
