OSTRACION UNDECIM-ACULEATUS. 
of all is horizontal, the two first extend laterally, the last backwards and 
outwards. The inferior or abdominal side slightly subovate and convex, 
narrow anteriorly, subtruncate posteriorly, and with a slight semicircular 
projection immediately under the tail. The plates of the back are irregularly 
five or six sided, each having its margin prominent and considerably raised 
above the disc ; those of the sides present a like irregularity in regard to 
form, but their margins are less distinctly indicated, and there is no very 
marked inequality between them and the discs. The plates of the sides of the 
head are small, and fashioned like those of the back. The plates of the belly 
have their margin very prominent, and their disc hollow; the former is 
smooth, and the latter is studded with pellucid granules ; the anterior portion 
of the back, the sides of the head, and all the angles are also more or less 
granular. The anal is situated considerably behind the dorsal fin, and both 
are rather fan-shaped. Tail subcylindrical ; caudal fin moderately long, and 
square or slightly rounded behind. The pectoral fin has the. upper rays 
longest, the lower one shortest. 
DIMENSIONS. 
Inch. Lin. 
Length from the nose to the hinder edge 
of the cuirass 5 6 
Distance between the nose and the base 
of the dorsal fin 3 0 
Inch. Lin. 
Distance between the nose and the base of , 
the anal fin 3 8 
between the nose and the bran- 
chial opening 1 2 
Young. — In young specimens the back is very narrow, and the lower or 
abdominal parts very broad and bulging; the spines, in proportion, are more 
elongated, and the figure altogether is less regularly angular. 
Inhabits the seas about the Cape of Good Hope, and also the Indian Ocean. Specimens are 
frequently found on the beech after gales of wind, both to the eastward and northward of Cape 
Town, and individuals are occasionally taken in nets in Table Bay. 
