MURAENOSAURUS? REEDII, SP. NOV. AND TRI- 
CLEIDUS? LARAMIENSIS KNIGHT, AMERICAN 
JURASSIC PLESIOSAURS 
MAURICE G. MEHL 
The University of Chicago 
The material upon which this paper is based consists of the more 
or less fragmentary remains of two plesiosaurs from the Jurassic of 
Wyoming, furnished by Professor Wm. H. Reed, curator of verte- 
brate paleontology in the University of Wyoming. It is in honor 
of Professor Reed that the name Muraenosaurus? reedii is given to. 
one of the species which proves to be new. 
Muraenosaurus ? reedit, sp. nov. 
This specimen consists of a fairly complete right coracoid and 
a part of the left one, parts of the right and left pubes and ischia, 
numerous dorsal and caudal vertebrae, several ventral ribs, and a 
nearly complete left pectoral paddle. The-species, judging from the 
remains at hand, is one of the most primitive found in America and 
in all probability belongs to a new genus. The material is hardly 
complete enough for a generic description, however, and the 
species is therefore provisionally placed with the English genus 
Muraenosaurus Seeley,, which it closely resembles in several 
respects. The primitive form of this species is shown in the rela- 
tively long humerus with its moderately expanded distal end, the 
long radius, and the relatively small degree of hyperphalangy. 
Although there is no way of determining the length of the neck, 
it must have been long, for the ischia are short and the association 
of these two things, long neck and short ischia, seems to be a rule 
that can usually be depended upon. ‘The similarity of this species 
with Muraenosaurus will be seen in a comparison with the following 
partial diagnosis of that genus by Andrews: 
In the shoulder-girdle there is a well-developed interclavicle, while the 
clavicles are generally greatly reduced, in some cases being mere films of bone 
t Andrews, Marine Reptiles of the Oxford Clay, Part 1, p. 77. 
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