108 Proceedings of the Iloyal Society 
a second instance, the end of a gland passed from under cover of 
the surrounding crypts, and then seemed to open by an obliquely 
directed mouth near the free edge of the spot. But upwards of thirty 
other spots examined with equal care gave me no evidence of gland 
mouths opening on them. Hence it would appear that these smooth 
surfaces on the mucosa are by no means necessarily associated with 
the mouths of the utricular glands, and one is disposed to conclude 
that the gland orifices are usually concealed amongst the crypt-like 
foldings of the mucosa. The very much greater number of the crypts 
than of the stems of the glands, negatives the idea of the crypts 
being merely dilatations of the mouths of the glands, so that in the 
Narwhal, as in Orca, the Pig, and Mare, the crypts are to be 
regarded as interglandular in position and produced by a hypertrophy 
and folding of the mucosa. 
Through the kindness of my friend Dr Allen Thomson, I have 
had the opportunity of examining a portion of the gravid uterus 
and chorion of a Narwhal, the foetus in which measured only 3J 
inches long. The free surface of the mucosa was gently undulating 
and traversed by shallow furrows, but no definite crypts could be 
seen. The gland-tubes were remarkably numerous, tortuous, and 
branching. I made a comparative measurement of their size, with 
that of the glands in my much more developed specimen, and found 
them to have only one-half the transverse diameter. The gland- 
stems inclined obliquely to the surface of the mucosa on which 
their orifices could occasionally be seen. The free surface of the 
chorion was not villous, but traversed by faint ridges, which without 
doubt fitted into the shallow furrows of the mucosa. Patches of 
epithelium-cells could be seen covering the surface of the chorion. 
It is clear therefore that in the Narwhal, as I have elsewhere de- 
scribed in the pig, the villi do not form on the surface of the chorion, 
nor the crypts on the surface of the mucosa, until the embryo has 
reached a stage of development in which its body, though small, 
has assumed a form which enables its ordinal characters to he 
recognised. 
When I published my memoir on the placentation of Orca, I 
was under the impression that the crypts were lined by a pavement 
epithelium, and was not disposed to regard the crypts in the 
mucosa of that cetacean as secreting organs; but a re-examination 
