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SOME NEW BOOKS 
THE BACKBONED ANIMALS 
A CLASSIFICATION OF VERTEBRATA, RECENT AND Extinct. By Hans Gadow. 8vo, 
pp. xvii+82. London: A. & C, Black, 1898. Price, 3s. 6d. net. 
Tus is a valuable and convenient handbook for the use of students 
attending lectures on the vertebrate animals. It can also be used as 
a notebook, being printed on one side of the paper only. 
Dr Gadow defines the Vertebrata as “bilateral symmetrical 
animals with segmentally arranged mesoderm, with a central solid 
axis (Chorda dorsalis, extending through the whole length of the 
body, from head to tail, hence holochordate), dorsally of which lies the 
tubular central nervous system, ventrally the gut; the respiratory 
organs arise from the anterior portion of the gut.” He then proceeds 
to define the ‘sub-phyla’ and smaller divisions with commendable 
brevity and conciseness. As he remarks, there is no reason to 
enumerate any but the fundamental characters. “For instance, ‘the 
possession of visceral arches, one pair of which is modified into jaws,’ 
is a quite sufficient diagnosis of the Gnathostomata. The presence of 
an anterior and a posterior pair of limbs is probably quite as essential 
and peculiar a feature. There are not, and can never have been, 
paired-limbed vertebrata without visceral-arch jaws; consequently, 
wherever the converse is the case, we feel certain that the absence of 
limbs is a secondarily produced feature.” Dr Gadow also lays special 
stress on skeletal characters, not merely on account of their supreme 
importance, but also because the vast array of extinct animals can 
only be treated as skeletons. As he well observes, “we do not know 
that the Palaeozoic Fishes did possess an entirely venous heart, nor 
has it yet been shown that the embryos of Dinosaurs were surrounded 
by an amnion ; but we feel nevertheless certain, because of the laws of 
correlation which comparative anatomy allows us to deduct from the 
study of recent creatures. On the other hand, it is quite possible, even 
most likely, that the Triassic Pseudosuchia had no copulatory organ, 
and therefore this feature cannot be admitted into the diagnosis of 
Crocodilia, at least not if they are to comprise the Pseudo-, Para-, and 
Eusuchia.” Finally, the author is to be commended for his selection 
of generic names. The book is “meant to be used by the present 
generation,” and hence he employs those names under which the whole 
story of vertebrate anatomy and zoology has been written, ignoring 
certain recent papers which are rather literary essays than contribu- 
tions to knowledge. 
Dr Gadow recognises two sub-phyla of Vertebrata, namely the 
