112 FOUR-HEARDED ROCKI.ING. 



exactly in front. In this respect its structure may be easily 

 distinguished from that irregular formation which has been 

 referred to, and which may not occur again in the Five-bearded 

 Rockling. A further distinction is noticed in the much longer 

 extension of the thread, or process, which stands up before 

 the ciliated membrane behind the head. The ventral fins are 

 shorter than in the other species, and the head somewhat longer. 

 It is probable that its colours vary in some degree, according 

 to the nature of the ground; but usually, while the back and 

 sides are dusky and reddish, there is a whitish border to the 

 dark brown dorsal and anal fins. It has been known to measure 

 fifteen inches in length. 



