566 Reviews—Dr. Andrews’ Marine Reptiles, Oxford Clay. 
different skeletons; due to some extent, no doubt, to age and various 
stages of ossification, as well as to conditions of fossilization: and 
he makes the pertinent observation that ‘‘ If only a few skeletons had 
been preserved several forms would probably have been recognized 
and named’’. But with so large a series before him ‘‘it has been 
found impossible to distinguish more than a single species”. Few 
geologists will be inclined to find fault with this specific restriction, 
although ‘‘future investigations may render possible the diagnosis 
of others ”’. 
The restoration of the cranium of Ophthalmosaurus has been an 
exceedingly difficult matter, seeing that it was largely cartilaginous, 
and consequently the bones show few or no sutures, or surfaces of 
actual contact; indeed, but for the fact that in this collection of 
fossils only one Ichthyosaurian genus seems to be represented, it 
would have been a wellnigh hopeless task. Numerous specimens, 
illustrating all parts of the skeleton, are described in detail, and after 
a short account of the species there follows a catalogue of the very 
numerous specimens preserved in the Museum. 
The Plesiosaurs all belong to the one family of the Elasmosauride, 
characterized chiefly by the scapule meeting in a median symphysis 
which is continuous with the symphysis of the coracoids: and the 
scapule grow inwards (in front) below the clavicles and interclavicles. 
The clavicular elements become more or less reduced, and it is the 
variations in this reduction which supply some of the chief characters 
for the distinction of different genera. Four genera of Elasmosauride 
are recognized: MMurenosaurus, with three species; Picrocleidus, with 
two forms, only one of which is specifically named; Ziiclecdus and 
Cryptoclerdus, each with one species. Of these four genera two, 
Murenosaurus and Cryptocleidus, were so named by Professor Seeley, 
the first in 1874 and the other in 1892; while Prcrocleidus and 
Tricleidus are genera established by Dr. Andrews quite recently. 
The most perfect specimen in this collection is, perhaps, the 
Cryptocleidus oxoniensis, already mentioned as being mounted in the 
Museum and figured as the frontispiece; and this species has an 
additional interest inasmuch as it was first described by Professor 
Phillips in 1871 in his Geology of Oxford. 
Each genus is separately discussed by the author, and numerous 
specimens described in detail: the various parts of the skeleton, 
skull, vertebral column, pectoral and pelvic girdles, and limbs being 
treated separately and illustrated by plates and text-figures. Following 
the description of each genus is a brief account of the species referred 
to it, and a catalogue of the specimens preserved in the Museum. 
The volume is liberally illustrated, for besides the frontispiece there 
are ten lithographic plates and ninety-four figures in the text. Eight 
of these plates have been drawn by Miss G. M. Woodward with her 
usual care and artistic finish, and two are the work of Mr. A. H. Searle | 
and are equally worthy of commendation. The text-figures leave 
nothing to be desired in the way of clearness ; but, like so many text- 
figures in present-day publications, they are far from adding to the 
beauty of the page; many of them, too, are far larger than is 
necessary to show the required details; and might almost be called 
