1865. ] OF PHYSALUS ANTIQUORUM. 215 
not pretend to state with certainty, although I am inclined to believe 
it to have been of the latter nature; nevertheless I have thought it 
of sufficient import to be figured, so that the attention of future ob- 
servers may more readily be called to notice if such a structure exists 
in any specimen that may be dissected by them. 
Transverse sections of the penis at various points showed, as in 
ordinary Cetacea, the usual absence of median division in the corpus 
cavernosum ; at the root, however, there was an approach to sepa- 
ration by the aggregation of the vessels into two circular groups ; but 
towards the anterior extremity or point these were scattered more 
equally among the strong fibrous trabeculee. The canal of the ure- 
thra for its whole length was on the under side of the corpus spon- 
giosum : in this respect it differed from that of the Porpoise, which 
Hunter (doc. cit. p. 388) has described as being at first in its centre, 
and then coming to be on its under side. At the root the canal 
was roundish, but towards the free extremity more triangular in form, 
The strong, firm, fibrous sheath surrounding the corpus cavernosum 
was an inch thick in most parts. The glans penis was represented, 
for a considerable distance backwards, by a thick layer of vessels, 
chiefly veins, each, on section, of a slit-like shape, with pointed ends, 
and arranged with their broad surfaces superimposed upon one an- 
other on the fibrous sheath, excepting on its under side. Their ap- 
pearance in the transverse section was not unlike the open vascular 
sinuses of a pregnant uterus when cut vertically. 
The foregoing are the principal observations which I had the op- 
portunity of making on this specimen while in the fresh condition ; 
but I think it may be as well to add some notes on the osteology, as 
a contribution towards a fuller knowledge of its anatomy. This sub- 
ject has already been partially treated by Cuvier, Van Beneden, Dr. 
Gray, and others; but so much remains to be done to complete the 
anatomy of species of the group, that any details as to the structure 
of a single individual can hardly be deemed superfluous. 
Mr. Flower has made some original and highly useful observations 
on the condition of the bony epiphyses as a guide to age in the Ce- 
tacea (P. Z. 8. 1864, p. 384); and, availing myself of his remarks, I 
agree with him in classing the Rosherville specimen of Physalus 
antiquorum in the third or last stage, that is, a perfect adult, 
although the animal was no more than 60 feet long. For, on exa- 
mination, I find all the epiphyses of the vertebree are firmly anchy- 
losed, so much so that the line of junction is with difficulty made 
- out. The same may be said of the upper and lower epiphyses of the 
humerus. The proximal epiphyses of the radius and ulna are like- 
wise firmly adherent to the shaft by bony union; but, on the other 
hand, the distal epiphyses of these bones are only united at their pe- 
riphery, for a broken portion in each discloses the centre to be in- 
completely ossified, and not attached to the diaphysis of the bone. 
The sutures of the skull are also well-nigh obliterated, excepting 
such as remain more or less persistently separable. 
The general appearance of the skull shows no points strikingly 
different from what is usually found in P. antiquorum; and the 
