NORTH SEA INVESTIGATIONS. 189 
colorate condition and the partial arrest of the migration of the upper 
eye met with in so-called “ Cyclopean ”’ examples. In making full 
reference to the recent important memoir of Messrs. Cunningham and 
MacMunn on the Coloration of the Skin of Fishes (Phil. Trans., 
1894, p. 765), such additional material as I have examined points to 
a general acceptance of the opinions on ambicoloration therein formu- 
lated, but several minor details require a few words. ‘Thus the re- 
striction, apparent from the examples studied by these authors, of 
pigmentation of the lower side to the region posterior to an imaginary 
line drawn through the pre-operculum, in partially ambicolorate but 
structurally normal turbot, does not hold good in the case of one which 
has recently come into my hands. No malformation is apparent, but 
the anterior border of the continuous pigmentation is formed by a 
line which passes from the origin of the dorsal to the angle of the pre- 
operculum, and thence forward again across the lower part of the gill 
cover to the anterior end of the isthmus. In addition, the maxilla 
and a great part of the mandible are also coloured. Accordingly, while 
admitting that Cunningham and MacMunn’s limitation covers the 
great majority of cases, we must hold that any degree of ambicolo- 
ration, short of completeness, may occur in the turbot without apparent 
structural abnormality. 
The authors note that reliable records of the ‘ Cyclopean malfor- 
mation” are limited to certain genera and species, which do not 
include the sole, but are unable to discover any “ correlation between 
the occurrence of this malformation and any peculiarity of the 
species in which it occurs.” So far as the sole is concerned, this 
species has a skeletal peculiarity in the form of a great blade-like 
ligament bone interposed between the base of the front part of the 
dorsal fin and the top of the skull, which is not present in any of the 
genera in which the malformation has been observed. Taking into 
consideration the relationship of the parts concerned in the mal- 
formation, I suggest the possibility that this feature may supply the 
missing correlation. It is also possible, and perhaps more likely, that 
the burrowing habits of the sole would be fatal to the survival of a 
“‘ Cyclopean ”’ example of this species, since the length of the “ hook ” 
necessitated by the great forward extension of the dorsal would be 
a serious impediment to it, while all available evidence supports the 
opinion of the authors that their abnormal flat-fish do not cH at 
all in habit from their normal brethren. 
The authors note the frequent occurrence in the brill of a form of 
ambicoloration in which spots of pigment occur in a series along the 
interneural and interhzemal regions of the lower side, and Bateson (in 
a communication to the Zoological Society which I have not yet 
in print) has pointed out that these spots are symmetrically arranged 
