Reviews—J. W. Davis—Fossil Fishes. ie 
subject have been brief, scattered, and desultory, and our knowledge 
of the fishes of the British Coal Measures has in some respects— 
though not in all—lagged behind that of certain corresponding 
foreign strata. About fifteen years ago the Paleontographical 
Society published the first part of two memoirs proposing to include 
a large portion of the subject; but nothing further has been heard 
of these, and there seems to be no immediate prospect of their 
continuation. It is, therefore, with considerable satisfaction we 
are able to announce, that the Royal Dublin Society has decided 
to publish a series of descriptions and figures of all the more 
important fish-remains from the British Coal Measures that are 
available for the purpose. The work has been undertaken by 
Mr. James W. Davis, who, by his monograph of 1888, has already 
given a definite meaning to the long series of manuscript names 
applied by Agassiz to the fragmentary ichthyolites from the Lower 
Carboniferous, and who has himself made many contributions to 
our knowledge of the fish-fauna of the Carboniferous Period. The 
memoir will appear in annnal instalments, and the first part has 
now reached us. 
This opening part deals with the Elasmobranch family of 
Pleuracanthide, of which numerous fragmentary remains occur 
in all Coalfields, and of which so many tolerably complete skeletons 
have been discovered in Germany, Bohemia, and France. Hitherto, 
the British material has not been examined in detail with reference 
to these discoveries on the European Continent, or in comparison with 
certain discoveries of Pleuracanth skulls in Texas; and Mr. Davis’ 
survey is thus in great part new, especially as regards the associated 
groups of teeth and remains of the endoskeletal cartilage. Nine 
beautiful plates, by Mr. Crowther, serve to illustrate the text, and 
will form a contribution to the subject of permanent value, however 
much future discoveries of skeletons may cause modifications in the 
taxonomy and interpretations adopted. One can only regret that 
the known British fossils should as yet remain comparatively 
fragmentary. 
The Pleuracanthide are placed by Mr. Davis in the order 
Ichthyotomi, and the genus Pleuracanthus is retained in the wide 
sense in which he and Egerton proposed to regard it years ago. 
It is pointed out still more clearly than before that there exists 
every possible gradation between the spines named Pleuracanthus 
and those named Orthacanthus ; and one specimen is described (p. 720, 
pl. Ixvi.) in which it is proved that there occur in a single mouth 
teeth of all the three forms determined by Fritsch as characteristic 
of Pleuracanthus, Orthacanthus, and Xenacanthus respectively. It is 
also shown that teeth with round cusps, and others with compressed 
keeled cusps, occur in one and the same jaw, thus confirming an 
observation already made by Koken in the Permian Pleuracanths 
of Germany. The teeth, indeed, prove to be of little or no value 
for the diagnosis of species; and for the systematic arrangement of 
the fossils Mr. Davis relies upon the characters of the spines. 
One fossil from the Yorkshire Coal Measures is interpreted as a 
