20 
FOSSIL REPTILIA OF THE 
there, in proportion to its length, than in the PI. dolicJiodeirus or than in the 
PI. rostratiis ; its anterior margin, as in the skeleton Tab. V, is more straight than in 
those species. The antibrachial bones ( 54 , 55 ) show intermediate proportions of 
length and breadth between those in PI. dolichodeirus (Tab. I, fig. 2) and PI. rostratus 
(Tab. IX). They present the usual characteristics of radius ( 54 ) and ulna ( 55 ) in the 
present genus, and they are of equal length. The hand measures two feet in 
length, and is somewhat longer in proportion to the arm and forearm than in the 
two above-cited species ; it also shows rather more breadth. The carpus consists of 
six bones, three in each row, and with less inequality of size. The distal bones 
occupy an equal breadth with those of the proximal row, and do not allow the base 
of the fifth metacarpal to extend backward to the proximal row, as in the species 
of which the carpus is figured in Tab. XIV, The bases of the five metacarpals 
(in Tab. VIII, 57 ) are on the same transverse line ; and if this specimen should truly 
exhibit the relative position of the bones of the pectoral fin, characteristic of the 
species, it adds a well-marked distinction of the PL liomcdospondyJiis. The first, or 
radial, or innermost metacarpal ( 57 ), supports a short digit of three phalanges ; the 
second a digit of seven phalanges ; the third the same ; the fourth has a digit of six 
phalanges ; the fifth is obviously imperfect. 
The pelvic limb (Tab. VIII, 65, 69) is 3 feet 9 inches in length ; the femur (65) is 
14 inches long and 7^ inches across the distal end. The tibia and fibula are respec- 
tively longer than their homotypes the radius and ulna ; the foot is 2 feet in length 
and 1\ inches in basal breadth. The tarsal bones are similar in number and arrange- 
ment to those of the carpus ; and as the bases of the five metatarsals ( 69 ) are in this 
limb also on the same transverse line, I have the greater confidence in the natural 
structure being here shown in both limbs, and that they thus exhibit a distinctive 
character, of specific value, from the other Plesiosauri described in the present 
Monograph. 
Plesiosaurus rostratus, Owen. Tabs. IX — XIII. 
The specimen on which this species is founded was obtained, in 1863, by Edward 
C. Hartsinck Day, Esq., F.G.S., from the Lower Lias at Charmouth, Dorsetshire, by 
whom it was transmitted to London for inspection, and it has been purchased 
by the Trustees of the British Museum, where it is now exposed in the gallery of 
Geology, It is figured, one ninth of the natural size, in Tab. IX. 
This skeleton, like most of the plesiosaurian ones that have come under my obser- 
vation, indicates the ordinary and tranquil character of the death and burial of the 
individual; it has sunk entire, relaxed, and prone, with outstretched limbs, in its 
matrix, when this was soft and yielding ; and, as decomposition loosened the liga- 
