584 BAIIIXE. 



distributed over this upper surface numerous nail-like tuber- 

 cular spines, each of which has an oval osseous base ; the 

 margin of the base entire, with a central projecting crooked 

 shank or spine directed backward. Two of these broadly- 

 based spines occupy the central ridge of the nose ; others, to 

 the number of thirteen or fourteen, are distributed over each 

 side with some regularity, and similarly disposed on the two 

 sides. The dorsal ridge of unequally-sized spines begins a 

 short distance between and behind the temporal orifices, one 

 or two small spines occurring between each of the larger ones : 

 this single line of spines extends to the origin of the tail, 

 where three rows of spines begin and are continued along it, 

 forming a series of powerful weapons. The tail is furnished 

 with two membranous fins on the upper central ridge, and 

 ends with a small dilatation. The prevailing colour of the 

 upper part is brown, with numerous lighter-coloured spots, 

 and sometimes, as has been noticed already, with one larger 

 rounded spot on each pectoral. Young males and females 

 have fewer spines on the body than old males, and both 

 sexes attain some size before they put forth any ; they have 

 frequently also but one row of spines along the tail. The 

 colour of the under side is pure white, with a few spines only 

 on each side. The teeth of the adult male in this species are 

 decidedly different from those of the female, as shown in the 

 woodcut at the top of page 552 ; those represented on the 

 left hand being from a male fish, and those on the right from 

 a female fish of the same size, and representing one-half of 

 the inside of the mouth of each as seen from behind. 



