Reviews—Prof. A. Gaudry’s Permian Reptilia, ete. 165 
In the 4to. memoir on Actinodon cited above Prof. Gaudry gives 
us a full description of the magnificent series of remains of this 
interesting Labyrinthodont, of which preliminary notices have been 
published in previous works. The most important of these remains 
is the nearly entire skeleton exceeding two feet in length, of which 
a full-sized representation of the dorsal aspect is represented in 
plate i. of this memoir. In this skeleton the skull, vertebral column, 
pelvic girdle, and limbs are beautifully preserved; and we are 
glad to be able to inform our readers that Professor Gaudry 
has kindly presented a cast of this fine specimen to the British 
Museum. Other specimens exhibit the three thoracic plates on the 
Fra. 1. Ventral aspect of the thoracic buckler of Actinodon Frossard:. Reduced, 
ent. interclavicle ; ep. clavicles; s.c/. supraclavicle; 0. scapula. 
ventral aspect of the body (Fig. 1), which are generally correlated 
with the clavicles and interclavicle, and which preseut a strong 
general resemblance to the probably homologous ento- and epiplastra 
of the Chelonia; while other examples exhibit the dermal scutes 
covering the greater portion of the ventral aspect of the body. 
Actinodon belongs to a group of Labyrinthodonts confined in Europe 
to the Carboniferous and Permian epochs, and characterized by the 
so-called ‘rhachitomous’ structure of the vertebre (Fig. 2). In 
such vertebree the body, or centrum, is imperfectly ossified, and 
consists of two lateral elements termed the pleurocentra (pl. ¢.), and 
a median, horse-shoe-like, piece known as the intercentrum or hypo- 
centrum (i.c.). Considerable discussion has taken place as to the 
precise homology of these elements, into which it would be out of 
place to enter here; but it may be observed that the general balance 
of opinion is in favour of regarding the hypocentra as the repre- 
sentatives of the centrum proper, while the intercentrum corresponds 
to the intervertebral wedge-bones of Sphenodon, and is theretore a 
true intercentral element. M.Gaudry, however, does not quite agree 
with these conclusions. 
In Europe this group includes, among others, Archegosaurus, 
which is both Carboniferous and Permian, Euchirosaurus (Fig. 2) of 
the French Permian, Cochleosaurus from the corresponding beds of 
Bohemia, and Platyops from those of Russia. In Africa it is 
represented by Rhytidostens of the Karoo system; in India by 
Gondwanosaurus of the Bijori beds of the Gondwanas; while the 
