ANATOMY OF BALDEN OPTEEA ROSTEATA. 
203 
No parasites were discoverable on the external surface of the animal. 
The integument on the geniothoracic surface of the body was arranged in a series of 
longitudinal folds or plicae, which at their origins, immediately beneath the rami of the 
lower jaw, were flat and inconspicuous, but as they extended down towards the thoracic 
region they became enlarged and much more numerous; subsequently, as they 
approached the abdominal parietes, they decreased in number but increased in width, 
being finally lost in the neighbouring skin. 
The arrangement of these folds was by Hunter very appropriately compared to the 
bands of a ribbed stocking. There were fifty-four of them on the thoracic surface ; the 
average depth of the furrow or interval between each of them measured about three- 
eighths of an inch, and on stretching the skin, which this peculiar arrangement 
greatly facilitated, the outline of each rib or band was somewhat rectangular, thus 
| | j | | | ; five of them, on the anterior or geniothoracic region of the 
body, occupied a space of 3 inches, whereas the same extent of surface posteriorly, or 
towards the pudendal outlet, contained but three such folds. The subcutaneous tissue 
being highly elastic, rendered the skin in this region very distensible 
No bristles were found at the extremity of the snout, as described by Knox in the 
specimen of the same sex examined by him in 1839. 
The epidermis was extremely thin and easily separable, coming off in delicate flakes. 
The colour of the animal on the back was of a dark bluish black, merging gradually 
into a pale pinkish white on the thorax and abdomen. The pectoral extremities or 
flippers were of the same bluish-black colour, with a pinkish-white band crossing the 
central part of each of them. The tail was of a uniform dark blackish hue on both 
surfaces. 
The eye was situated above and a little in front of the commissure of the lips ; it was 
comparatively small and oval in shape, with the major axis running parallel to that of 
the body of the animal. 
The external auditory foramen was a very minute, oval, slit-like pore situated on a line 
with the commissure of the lips, and about 7^ inches behind the posterior angle of the eye. 
The external nares or blowholes occupied the summit of the head, but were not ele- 
vated above its general surface ; they were two, curved, linear, slit-like outlets, each of 
them about 4^ inches long, running in the direction of the long axis of the body, with 
their convexities turned towards the mesial line ; these semilunar orifices were separated 
of the nose ; according to the measurements given by Knox it would appear that in his specimen it was situated 
nearer to the tail, and in the animal figured by Hunter it is represented as being placed still further back ; in 
the present instance, on the other hand, this protuberance was situated anterior to the position mentioned by 
Dr. Gray. 
Upon the situation of this fin Eschricht founds the distinction between his two varieties, Graenlandica and 
Bergensis, with the latter of which our specimen seems to agree, not in this point alone, but likewise in 
another character of that variety, viz. the non-coalition of the lateral processes of the fifth and sixth cervical 
vertebrae. 
Dr. Gray also refers to the position of this fin as being situated posterior to a line drawn perpendicularly 
upwards from the pudendal fissure. In the present case it was placed vertically over this outlet. 
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