28 DEEP SEA FISHES. 
at the depth of two hundred fathoms or more.” The greatest depth noticed 
for any of the species of Squalus is that by Vinciguerra, of three hundred 
and twenty-eight fathoms for S. uwyatus Raf. in the Mediterranean. 
Centroscyllium nigrum psp. u. 
Plate 1, fig. 2; Plate IV. and V., Anatomy ; Plate LXIX., fig. 1, Lat. Syst. 
The proportions and shape of this species are similar to those of Centro- 
scyllium Fabricii Reinh., or of C. granulatum Giint. The type is moderately 
slender and elongate, and is compressed behind the shoulders; the body 
cavity occupies about three fifths of the entire length. Head large, broad, 
depressed, inclusive of the gill openings little more than one fourth of the 
total. Snout broad, in length nearly equal to the width of the forehead, 
broadly rounded across the front. Nostrils at the edge of the snout, nearer 
to the end than to the eye. Eye large, lateral, without a nictitating mem- 
brane; orbit with a more distinct angle on the back than on the front 
border. Mouth wide, inferior, curving forward moderately in the middle, 
where it extends but little forward of a line joining the hind borders of the 
orbits, with a short groove around each angle, from which another groove 
continues backward nearly half-way to the first gill opening. Teeth small, 
numerous; upper with three erect, slender, acuminate cusps, median cusp 
largest, and outer cusps each with a rudimentary cusp on the outer side; 
lower with five similar cusps, median largest, and outer two small, Plate IV., 
fig. 5, 6. Gill apertures five, hardly as wide as the eye, posterior two of 
each side closer together and near the base of the pectoral. Spiracles 
medium, superior, transversely crescent-shaped. Rostral ampullz numer- 
ous, Plate IV., fig. 3, those of the top of the head numbering a hundred, 
more or less, and those below the snout nearly twice as many. 
In the skull, Plate IV., fig. 1, 2, and Plate V., fig. 1, the affinities of this 
shark to Squalus acanthias Linn., to Etmopterus spinax Linn., and to Centro- 
phorus granulosus Bl. Schn. and their allies are very apparent. The entire 
skull is shorter and broader and the rostral cartilage is broader and shorter 
than in either of the mentioned forms. The width across the olfactory 
capsules is considerably greater, but the post-orbital processes are nearly 
of the proportions of those of C. granulosus. Above the symphysis of 
the upper jaws on the lower side of the skull there is a slender process, 
Plates IV. and V., fig. 1. At each side of the mouth there are three 
