536 DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 
three superciliary hairs, or rudimentary eyebrows, varies from half to one inch long; 
and they are light-coloured and bristle-like in texture. 
The ball of the eye is full; the pupil perpendicular, ovoid, and about 0:3 inch in 
length. This is the case under ordinary conditions; but the pupil alters in a most 
extraordinary manner. At times it opens full and round, even larger than the dimen- 
sion just mentioned, or about equal to the circle I have shown in the diagram, no. 3, 
fig. 10; again, as it decreases, it assumes the vertical oval figure (no. 2), and as it 
contracts still more, almost to a pinhead’s diameter, the shape becomes nearly triangular 
(vide no. 1). Imade careful observations of this remarkable pupillar dilatation and con- 
traction. I found that in the day-time, and especially with clear bright sunshiny weather, 
the maximum of contraction took place; when, however, the day was gloomy and dark, 
a more opened condition obtained; moreover, during the afternoon and as twilight 
crept on, so did the pupil slowly increase in magnitude, and had expanded ere 
nightfall to its fullest extent. Accompanying these changes, as marked a phenomenon 
of colour ensued. When contracted, the pupil glistened as a bluish iridescent point; 
dilating gradually, it assumed an opalescent hue, and at length looked as if a filmy 
curtain had passed across the ball of the eye. My attention was called to these diurnal 
and nocturnal changes from doubts as to whether the animal suffered from cataract. I 
believe them, however, to be the ordinary natural phenomena incident to the vision of 
this creature, although it is possible they were more apparent in this instance than 
usually may be the case. Doubtless physiologically some purpose is subserved, such as 
night-fishing, which, according to Lecomte, is the habit of the animal; but at all events 
this peculiarity of colour presents contrast to the full, soft expression of eye belonging 
to most of the Earless Seals. 
9. Har.—The division of the Seals into two groups, the Eared and Earless, seems a 
natural one. The very diminutive-sized ears, even if only viewed as a minor character 
in the total outward aspect, are so obviously distinctive and peculiar-looking in the 
living animal as to attract immediate attention. 
In Otaria jubata the external organ of hearing is situated about the end of the 
middle third of the head, taking the latter in its longitudinal axis. ‘The eye is placed, 
in relation to the ear, at the anterior end of the same middle third. A line carried 
through these organs would reach the upper part of the muzzle in front and the lower 
portion of the occiput behind. ‘The absolute distance between the posterior canthus of 
the eye and the anterior portion of the root of the ear is 5 inches. 
The pinna, or auricle, in its ordinary contracted condition, is a small conical and 
backwardly projecting body, an inch in length, and half an inch in breadth at its base 
(fig. 11). Behind it there is a slight indentation or shallow grooved depression in the 
skin, in which the ear, when thrown backwards, is partially embedded. 
The auricle is externally clothed with short, close-set, light golden-coloured, shining 
hairs; and the hair in the shallow fossa already spoken of is of a similar colour. The 
