C 193 ] 



Notes and Memoranda. 



An Observation of the Colour-changes of a Wrasse. 

 Labrus macu/atus. Donovan. 



The common wrasse of our coasts is well known to exhibit, as a species, 

 an almost endless variation of colour. To what extent the different 

 colour-patterns are individual or congenital, and to what extent they 

 may be produced in the same individual by different stimuli, appears 

 to be a question worthy of careful examination. We propose at 

 present to deal chiefly with the observation of a single specimen. 



On the 4th October, 1897, trawling among the red-weed and zostera 

 beds at the mouth of the Yealm, we took a wrasse 16 inches in total 

 length. Captured most probably in the zostera, it exhibited a uniform 

 green colour, without any markings except the inevitable indistinct 

 dark spot at the base of the last dorsal rays. 



Confined for a few hours in a tub on board the launch, it underwent 

 no colour- change. It was then placed in a shallow, open tank, with 

 black walls, under an iron shed at the back (N.) of the Laboratory. 

 The next morning, while retaining the general green colour, it showed 

 also some faint grey transverse patches on the sides. The fish 

 remained in this tank until the 2nd December, when it was found 

 to have undergone a further change. The ground colour was pale 

 olive-grey, diversified with dark grey transverse bars and patches 

 on the back and sides, and with whitish blotches on the fore part of 

 the abdomen. This pattern is very common in the Plymouth district. 

 It may be described with sufficient exactness as follows: A number 

 (often four) of dark transverse bars pass from the dorsum to the region 

 of the lateral line. The first originates below the first rays of the 

 dorsal fin, the last below the extremity of that organ. These bars 

 have no regularity of outline and are often split into two by the 

 intervention of a pale transverse stripe. Another bar occurs on the 

 caudal peduncle. About the lateral line the dorsal transverse bars 

 are irregularly continued backwards by short longitudinal patches ; 

 below these originate a series of ventral transverse bars which 



