320 Reviews—Dr. Traquair on the Platysomide. 
are intimately allied to the Paleoniscide, and that the suborder 
‘Lepidopleuride’ must be abandoned,—to follow up this idea more _ 
in detail is the object of the present paper. I shall, therefore, first 
review the structural features of the Platysomidz, genus by genus, 
and from the facts thus acquired, endeavour, in conclusion, to justify 
my views as to their real position, and as to the validity, or not, of 
the suborder established by Prof. Young.” 
Then follow interesting details relating to the ‘“‘ History,” “ Geo- 
logical Distribution,” and “ Structure,” of each genus, including 
notes or descriptions of the species appertaining to each. The 
structural descriptions are founded mainly upon original examination 
and study of specimens not available to the earlier students, and 
notably upon many examples in the celebrated collection of Coal- 
measure fishes belonging to Mr. Ward, of Longton. 
The author’s extensive and well-known knowledge—practical and 
theoretical—of the dental, and the external and internal skeletal 
structure of fishes, renders this portion of the memoir of exceeding 
value; inasmuch, as the gradations in form and character of special 
parts, namely, the dentition, bones of the head, and scales, denoting 
the degree, and also the order, in which the respective genera ap- 
proach or diverge each from the other, with the variations in external 
form consequent thereon, are fully considered and discussed. And 
although this descriptive portion is necessarily technical, it is pre- 
sented to the reader in his usual clear and intelligible manner. Our 
space will not permit of long quotations, and abbreviation is hardly 
practicable ; to be understood the descriptive details must be read in 
connexion with the excellent figures which illustrate the text. 
The new species described are only two, namely, Mesolepis micro- 
pterus, 'T'r., and Platysomus tenuistriatus, Tr.; both from the Lower 
Coal-measures of Derbyshire. On the other hand, P. declivus, Ag., 
is erased from our lists of British fossils, the species having been 
founded upon a distorted specimen of Hurynotus ; and to this genus 
is also referred the P.? insignis of De Koninck, from the Belgian 
Carboniferous Limestone. 
The reasons for allying the Platysomide with the Paleoniscide, 
and not with the deep-bodied fishes constituting the families Dape- 
diidee and Pycnodontide ; together with the details of the special 
points of differences in the anatomical structure of the fishes of each 
group upon which he bases his conclusions regarding their affinities, 
are succinctly, and we think we may safely add, convincingly stated. 
The structural points in which the Platysomide resemble the Dape- 
diidee and Pyenodontidz being few, and the differences many and 
important. Whilst the anatomical characters which assimilate the 
group to the Paleéoniscide are numerous; nevertheless, he admits 
that the points of difference are also many and striking, but “are 
quite insufficient to conceal the close affinity between them”: and 
regarding which our author observes, that ‘ weighing these points 
of resemblance and difference together, it is quite obvious that the 
latter are of a much more superficial nature than the former; in 
other words, the Platysomid type is simply a modification of the 
