THE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
[SIXTH SERIES.] 
No. 96. DECEMBER 1895. 
LVIII.—The Pectoral and Pelvic Girdles of Murenosaurus 
plicatus. By C. W. Anprews, F.G.S., Assistant in the 
British Museum (Natural History). 
PHILLIPS, in the ‘ Geology of Oxford’ (p.313), described under 
the name Plesiosaurus plicatus certain cervical and dorsal 
vertebree from the Oxford Clay of Shotover. From the same 
horizon in the neighbourhood of Peterborough numerous more 
or less complete skeletons of a species of Plesiosaur have been 
collected in which the vertebra are of a similar character. 
These specimens present a considerable range of variation 
both in size and in the degree to which fusion of the elements 
of the vertebree has taken place; in some the neural arches 
and cervical ribs are still quite free, in others they are co- 
ossified with the centra. It was on one of the skeletons in 
which the latter condition obtains that Professor Seeley 
founded his description of Murenosaurus Leedsi. The genus 
Murenosaurus is distinguished from Cryptoclidus, to which 
the greater number of specimens from this locality are 
referable, by the enormous length of the neck (about seven 
times that of the head), caused not only by the much larger 
number (forty-four) of cervical vertebrae, but also by the 
greater length of the individual centra. There are also nume- 
rous differences in the pectoral girdle and limb-bones which 
fully establish the right of this type of Plesiosaurian skeleton 
to generic rank, 
Ann. & Mag. N. Hist. Ser. 6. Vol. xvi. 31 
