1116 
SCANDINAVIAN FISHES. 
The snout is prolongated in a securiform shape. The 
posterior side-margins of the disk are arcuate, with 
a slight inward curve near the tip of each pectoral fin. 
The ventral fins are conically pointed and rounded, 
rather long, their length, measured from the sacral 
prominence, being not much less than 1 / 3 of the entire 
length of the tail, measured from the same point. The 
body as a whole is flat and not fleshy, its depth at 
the shoulder-girdle being only about 9 % of the greatest 
breadth of the disk. The tail is furnished, as in the pre- 
ceding Rays except the Thornback, with two juxtaposited 
dorsal tins, often united at the base. The hind margin of 
the posterior lies half a fin-length from the tip of the tail, 
which bears above a low and almost semicircular caudal fin. 
The length of the head to the occiput measures in 
specimens 1 m. long about 18 % of the length of the body 
or 30 % of the breadth of the disk. The length of the 
snout as stated above distinguishes the Shagreen Skate, 
as well as the following species, from the preceding 
forms of the genus, but the distinction is least- marked 
in the Shagreen Skate, as appears from the relation 
between this length and the least interorbital width of 
the forehead. The latter is at least about 30 — 35 % 
of the length of the snout from the anterior margin 
of the eyes. The longitudinal diameter of the eyes is 
about half the interorbital width. The spiracles, which 
are almost transversely set, are of about the same size 
as the eyes. The mouth is broad and curved, power- 
fully armed with teeth. The form of the teeth is also 
highly characteristic, and among the other Scandinavian 
Rays there is none with whose dentition it can be con- 
fused. Each tooth (fig. 320, a) lias a fairly long, un- 
guiform crown, subulate at the tip, with somewhat 
compressed sides and without other indication of the 
ordinary basal rim than a very small intumescence on 
each side. The largest teeth are set in the middle of 
the jaws, and their size decreases towards the corners 
of the mouth. All these teeth are arranged in about 
60 regular, longitudinal rows, which, in consequence 
of the length of the pointed crowns, the superimposed 
(imbricated) position thereof, and the fixed intervals 
between the rows, have a resemblance to thin ridges, 
fitting in between each other when the jaws are closed. 
The internasal width is about V 5 — 1 / 3 greater than the 
least interorbita-1 width (120 — 133 %), somewhat more 
than half (55 — 60 %) of the distance between each 
nostril and the tip of the snout, and about 1 2 % of that 
between the tip of the snout and the anus. 
Among all the Scandinavian Rays the present spe- 
cies has the most shagreened skin. The whole upper 
surface of the body is covered everywhere with dense, 
but very short spinuke, partly pointed with stellate 
base, partly granular and hardly distinguishable to the 
naked eye. On the snout, both above and below, 
throughout the anterior side-margins of the disk, 
and throughout the upper and under surfaces of the 
tail, these spinulae show a somewhat greater develop- 
ment, and with their pungent tip, recurved in a hamate 
form, they greatly resemble, on a small scale, the aculei 
proper. The ventral side too is strewn with spinuke, 
but more sparsely, large patches of smooth and naked 
skin being left on the pectoral and ventral tins, in the 
anal region, and at other points. The ordinary aculei 
have an expanded, stellate or grooved, laterally com- 
pressed, and flat- base and a hamately recurved tip. 
Two short rows of small aculei, varying in number 
and size, are set on the rostral cartilage. In a semi- 
circle around the inner margin of each orbit runs a 
row of larger, but unequal aculei, the middle ones, 
however, often absent or lost. The spinal column be- 
tween the head and the scapular cartilage is followed by 
a series of aculei, 8 — 10 in number and not very large, 
and sometimes a row of still smaller ones skirts this 
series on each side; but- often only vestiges of these last 
aculei remain in the form of small, worn protuberances 
occupying the said places. Two rows on the back begin 
just behind the scapular cartilage, the aculei being at 
first quite low, but increasing in size a-s they approach 
the tail, along which the rows proceed parallel to each 
other, on each side of the median line and nearer to 
this than to the side-margin of the tail. In these 
rows the aculei are very densely packed, sometimes, 
as it were, extruding one another. The largest aculei 
lie in front of the middle of the tail; further back 
their size again gradually decreases. On the spinal 
column itself, behind the scapular cartilage and in the 
caudal region, there is no row of aculei. 
The dorsal side is of a plain yellowish gray, the 
ventral side of a translucent milky white, the muscles 
of the pectoral fins being visible, and the tips of the 
fins showing a bluish tinge. According to Montagu the 
back is of a plain grayish brown; but in one specimen 
he found a few black spots on this ground-colour. 
The external differences of sex are confined, ac- 
cording to Fries and Malm, to the ordinary cards of 
spines on the sides of the head and the outer parts 
