OSTRACION BICUSPES. 
of cuirass semicircular, the convexity forwards. Under surface nearly flat, 
and somewhat diamond-shaped ; the greatest width a little way behind the 
commencement of the second third of the body ; the hinder extremity of the 
under surface broad and triangular, its termination directly under the point 
which forms the upper elongation. The lateral or abdominal angles spread- 
ing particularly towards the middle of the cuirass ; towards the head they are 
rather obtuse, elsewhere thin and sharp, and each, when perfect, is armed with 
two or four short and slender spines, the longest and strongest of each side 
situated at the most diverging point, as represented in figure a. The plates 
of the cuirass are irregularly six or seven sided, and the surface of each is 
divided into six or seven somewhat triangular compartments, by the same 
number of narrow rugose ridges radiating from a common centre, and each 
compartment, like the ridges, is more or less rugose, from the existence of a 
number of small semi-circular granules. In consequence of a certain degree 
of regularity in the arrangement of some of these ridges, an appearance is 
produced as if the sides were crossed longitudinally by several rows of long, 
narrow, and oval compartments, arranged like links of a chain. The plates 
of the under surface six-sided ; those towards the head closely coated with 
granules ; those on the belly with four or six divergent ridges, and only a very 
few granules. Tail subcylindrical ; dorsal, pectoral, and anal fins square 
behind, and the first ray of each the longest ; caudal fin posteriorly slightly 
rounded, or square. 
DIMENSIONS. 
In. Lin. 
Length from the point of the nose to 
the hinder edge of the caudal fin ... 10 0 
Distance between the hinder angle of the 
eye, and the base of the dorsal fin ... 4 3 
In. Lin. 
Distance between the hinder angle of the 
eye, and the base of the anal fin ... 49 
Distance between the nose and the bran- 
chial opening 1 10^ 
In very young specimens (fig. b), the superciliary ridges are arched, sharp, 
and armed with two delicate compressed spines. The arch of the back is 
greater than in adults, and the abdominal angles are more expanded 
horizontally. 
Inhabits the seas of Southern Africa, and found most frequently in the hays of the South- 
eastern coast. 
