449 
of Edinburgh, Session 1881-82. 
as it came into my hands was 23^ inches long. It is not my 
intention to give a detailed description of the Shetland skull, as 
the cranial characters of this animal have already been recorded at 
considerable length by MM. F. Cuvier, Van Beneden, Gervais, and 
myself. But as these specimens were all females, it may be useful 
to point out some features of difference which it presented, and I 
shall especially compare it with the female skull in the Museum of 
Science and Art, Edinburgh. 
In the first instance, I give a table of comparative measurements 
of the two crania, expressed in feet and inches. 
Table of Cranial Measurements. 
Skull in* 
Museum 
of Science 
and Art. 
Shetland, 
Mesoplo- 
don 
bidens. 
Greatest height of cranium from vertex to pterygoids . 
Q1 
y 2 
10 
Breadth of cranium across middle of superior margin of ) 
11 1 
1 0 1 
orbits ..... ( 
x± 4 
Breadth of cranium between zygomatic processes of ) 
111 
1 1 1 
squamosals ..... \ 
J 2 
u 2 
Breadth between antorbital notches 
VS 
• 4 
7-1 
Breadth of occipital condyles .... 
I! 
*4 
4 
Premaxillae, greatest width behind anterior nares 
5 
41 
^2 
Premaxillae, least width opposite anterior nares 
41 
4 
Premaxillae, greatest width in front of anterior nares . 
4 
4 
Width of anterior nares .... 
If 
Itut 
Mandible, length of ramus .... 
184 
184 
Mandible, length of symphysis 
Qi 
y 2 
7ft 
Mandible, greatest vertical height of ramus 
^2 
4 
The cranial sutures were not quite so distinct as in the skull in 
the Museum of Science and Art. The upper borders of the rostral 
portions of the two premaxillse were not so much turned inwards, 
and the widest interval between these borders, near the base of the 
beak, was ly^- inch, and not |fh inch, as in that specimen. Instead 
of an open meso-rostral canal, a distinct meso-rostral bone occupied 
but did not entirely fill up the hollow between the premaxillse ; for 
this bone was divided into two not quite symmetrical halves by a 
mesial superior furrow, in which probably an unossified part of the 
meso-rostral cartilage had been lodged. This furrow was bounded 
behind by the anterior end of the mes-ethmoid bone, which extended 
* These measurements of this skull have already been published in my 
Report on the Bones of the Cetacea collected by H.M.S. “ Challenger,” 1880. 
t This mandible is imperfect. 
