518 Reviews—JTames W. Davis— 
generally here, but rather to direct attention specially to a single 
group of fossil fish-remains from the Carboniferous Limestone, in 
which the collection formed by the Harl of Enniskillen is exceedingly 
rich. These remains consist, for the most part, of detached teeth 
and spines of a great number of species of cartilaginous fishes 
evidently closely related to the existing Cestracionts, whose jaws 
(like the living Port Jackson shark) were armed with numerous 
obliquely-disposed crushing teeth which covered like a pavement the 
working borders of the mouth, while the anterior teeth were small 
and pointed. The dorsal (and often the lateral) fins of these old sharks 
were, like their modern representatives, armed with formidable 
spines more or less recurved and usually ornamented with ridges 
and tubercles and often strongly serrated. Of the rest of their 
remains we know nothing; for, as their skeletons were cartilaginous, 
they must have perished before they had time to become fossilized ; 
and it is rarely that more than two or three teeth are found asso- 
ciated together; hence the great difficulty which has always been 
felt by naturalists in correctly classifiying these remains, for although 
Prof. Agassiz named a great many specimens in MS., he described 
but very few. 
The work before us is a most praiseworthy effort on the part of Mr. 
J. W. Davis, of Chevinedge, Halifax, to gather up all the literature 
relating to these fragmentary fish-remains, and following Agassiz’s 
intentions, so far as they can be detected by his MS. labels on the 
large series of Mountain Limestone teeth and spines in the Ennis- 
killen collection, to name, describe and figure all these varied forms 
of Plagiostomatous fishes in a carefully prepared and exhaustive 
monograph. 
The author is probably indebted to the powerful interest of a 
noble Irish peer for the fortunate circumstance that his work has 
been published under the auspices of the Royal Dublin Society, and 
forms a part of the new series of their Transactions. The text fills 
274 quarto pages, and is illustrated by 24 chromo-lithographic plates, 
several of which are folding plates of large size. 
“The fish-remains,” writes Mr. Davis, “found in the Mountain 
Limestone formations have hitherto not proved very numerous, nor 
have they been discovered in a great number of localities, consider- _ 
ing the large area occupied by this group of rocks, its great vertical 
thickness, and the large extent to which it has been excavated for 
commercial purposes. The Limestone in the great majority of 
localities does not appear to contain any remains of fishes, and with 
the exception of the Armagh district and that of Bristol, other localities, 
including Wensleydale, Kendal, Derbyshire, and Oreton in Salop, 
have added few, either specimens or species, to enrich the knowledge 
of the ichthyic fauna of that ancient period. 
The fish-remains hitherto found in the Carboniferous or Mountain 
Limestone belong with few exceptions to the Plagiostomata—the 
sharks and rays—and consist of an almost endless variety of teeth, 
and a large number of spines. A very slight consideration of the 
anatomical constitution of an existing shark will give an idea of the 
