126 Reviews—Prof. EB. S. Goodrich—Cyclostomes and Fishes. 
The arrangement of the Selachians (Chondrichthyes) differs from 
most recent systems in the recognition of only four primary groups, 
the Holocephali and Euselachii (Selachii of Goodrich) being united to 
form a division co-ordinate with the Ichthyotomi, Pleuropterygii, and 
Acanthodii. In a natural system the two last-named should be placed 
first, the structure of their paired fins and the absence of mixopterygia 
indicating their generalization; of the other three orders, or sub- 
classes, characterized by the presence of mixopterygia, the Holo- 
cephali are quite as distinct from the Kuselachii as from the Ichthyo- 
tomi; the presence of a pharyngo-hyal shows that their autostyly is 
not a modified hyostyly, and Mr. Goodrich has failed to recognize 
that in the Selachians the terms ‘hyomandibular’ and ‘ epihyal’ are 
synonymous, and that the hyoid arch of the Chimeroids is essentially 
similar to the succeeding branchial arches. 
The classification of the modern Sharks and Rays is marred by 
some erroneous diagnoses and unnatural groupings; for example, the 
Jamnide are said to have no oro-nasal grooves, wide gill-openings, 
a pit at the base of the caudal fin and a keel on each side of the tail, 
and they are made to include Alopias, which has small gill-openings 
and no caudal keel, the Odontaspide, without or with vestigial pit 
and without keel, and Rhinodon, which differs from them 7 foto in 
the presence of oro-nasal grooves, the position of the gill-openings 
above the pectoral fin, etc., and indeed belongs to the Orectolobide, 
which family our author unites with the very different Scyliorhinidse 
(Seylliide). 
The Chondrichthyes are followed by the Ostracodermi, a provisional 
group; here some of Dr. Traquair’s recent interesting discoveries from 
the Silurian of Scotland are described and figured, and his views as to 
the relationship of the Ccelolepide, Psammosteide and Drepanaspidee 
are confirmed by Mr. Goodrich’s demonstration of the structural 
similarity of their exoskeleton. A new restoration of Cephalaspis calls 
for comment, as the organs shown by Dr. Smith Woodward to be 
‘ opercular’ prolongations of the head-shield, are figured and described 
as scaly, fin-like lobes, narrowed at the base, and projecting from each 
side of the body behind the head-shield; we venture to think that 
there is no justification for this interpretation. 
The Osteichthyes are divided into two main branches, the Dipnoi 
(with which the Arthrodires are provisionally associated), and the 
Teleostomi; it is not a little singular that this arrangement should be 
maintained by Mr. Goodrich, whose embryological researches have 
confirmed the secondary nature of the so-called ‘archipterygium’, and 
who first described the similar structure of. the Osteolepid and 
primitive Dipnoan scales and fin-rays, and the nearly normal arrange- 
ment of the bones of the cranial roof in Dipnoan genera such as 
Phaneropleuron and Ctenodus. 
The Dipnoi indeed scarcely differ from the Osteolepida except in 
their autostyly, and as this is plainly a modified hyostyly, from the 
structure of the hyoid arch, they should follow that group in a natural 
system. The modern Dipnoans are said to have internal nares, but 
as a matter of fact the nostrils are merely labial, as in some Eels” 
( Ophichthys), and the posterior ones cannot, be homologized with true 
