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. 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 



Distance between the nose and the hase 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. 



