A.—EXTERNAL CHARACTERS. 
The Plaice is not a large fish compared with many 
edible fishes, and the largest of which we find a record 
was 33 inches long, 21 inches high, and weighed 15lbs.t 
An average large plaice, however, would have an extreme 
measurement of 24 inches long and 14 high. The com- 
pression of the body is not from above downwards, as in 
the skate, but from side to side, so that when the fish is 
lying on the sea bottom its left side is downwards and the 
right only is exposed. For the sake of convenience, and 
for obvious reasons, we shall follow Traquair in referring to 
the right and left sides as the “ocular” and “ eyeless ” 
sides respectively. 
The eyeless side of the Plaice is colourless and flat, 
whilst the ocular side is pigmented and convex. The 
colour varies very greatly according to the nature of the 
sea bottom, and may be anything from grey to dark brown. 
The characteristic orange red spots (ocelli) form a row of 
about 6 on the dorsal fin, 15 or so on the body, one on the 
caudal fin, and another row of about 6 on the anal fin. 
Specimens with the eyeless side more or less coloured, and 
also reversed examples, are occasionally met with. The 
nature of the colouration has been investigated by 
Pouchet,f and by Cunningham and MacMunn.* We 
follow the latter memoir. If a superficial section be made 
of the fresh unprepared skin of the ocular side, two struc- 
tures only are apparent. These are the colour cells or 
chromatophores, situated largely in the dermis, but also 
found in the epidermis, and the opaque somewhat 
iridescent reflecting bodies or iridocytes. One layer of 
+ Thirteenth Annual Report for 1898 of Inspectors of Sea Fisheries 
(England and Wales), 1899, p. 10. 
{ Jour. l’anat. phys., 1877, No. 1. * Phil. Trans., 1893, B, p. 765. 
