156 
ZOOLOGICAL LITERATURE. 
that the change of position of the eye is not effected by its 
breaking through the skull. Further, he shows that Traquair 
was mistaken when he believed he had found a real asymmetry 
of the Pleuronectoid and Gadoid skulls in the supposed absence 
of the additional processes of the os frontis anterius and pro- 
prium. 
After having shown that Van Benedcn^s Turbot was really 
a young Pleuronectoid, the author proceeds to a detailed descrip- 
tion of those parts of the skull which are most subject to trans- 
formation. He' examines the skulls of the various European 
Pleuronectoids, and illustrates his text by neat figures of the 
skulls of the Plaice and Raniceps, in which the homologous 
parts are marked with identical numbers, from which it ap- 
pears that the Pleuronectoid skull is only apparently asym- 
metrical. This is confirmed by the authoFs researches into the 
development of the embryo of the Flounder, the first stages of 
which are described (p. 15) and figured (pi. 1. figs. 3-6). 
The author then describes very young PI. limandttj Solea vul- 
garis, and Rhombus vulgaris, of from 12 to 24 millims. in length, 
of which he observed a considerable number in a living state, 
and we regret much that we cannot enter into the details of 
these highly interesting observations. 
On p. 24 the author gives a very simple explanation of the 
abnormal condition of Pleuronectoids. The young Pleuronec- 
toid is forced by the excesssive depth of its body, enlarged by 
the development of the vertical fins, to lie on one side when 
resting on the ground. Neither the horizontal fins nor the air- 
bladder are sufficiently developed to sustain it in a vertical posi- 
tion as is the case in other fishes. The eye of the blind 
side has a tendency to turn towards the light ; and this eye 
carries at the same time the surrounding parts of the head 
with it, which is a matter of but little difficulty whilst the 
framework of the head is still cartilaginous. A commencing 
similar obliquity may be observed sometimes in a slight degree 
in very young examples of other fishes; and the author has 
found a very conspicuous obliquity in the skull of an example 
of Lepidopus. 
With regard to Steenstrup^s Plagusia/^ Hr. Malm doubts 
their pertinence to that genus, and thinks that also in this case 
the change of the eye may have taken place in the same manner 
as in other Pleuronectoids. 
The liecorder may add that Hr. Malm has informed him that 
he has read a paper on the same subject before the meeting of 
Scandinavian naturalists in Christiania, 1868, in which he ac- 
counts for the frequent occurrence of sinistral specimens of the 
Flounder by the fact that this species lives close inshore, and, 
therefore, is more exposed to the motions of the water than the 
other flatfishes; consequently individuals will frequently be 
