124 
FOSSIL REPTILIA OF THE 
usual. Forty-five pairs of tire long and regularly-curved ribs show the external longi- 
tudinal groove. 
The parial fins (PI. XXXII, figs. 4, 6) show a somewhat less disparity in the size of 
the pectorals and ventrals than obtains in Ich. communis and Icli. intermedins. Their 
framework has fewer and larger bones, and the fore paddle impresses one with its massive 
proportions compared with the vertebrae. The clavicles are relatively more slender than 
in Ich. communis, but of the usual form, diminishing at the two extremities. The scapula 
is relatively larger than in Ich. intermedins, and is thicker and more expanded at the 
hnmeral end ; its fore border is moderately concave and longer than the hind one. The 
coracoid (ib., fig, 3, 52 ) has a broad neck supporting a large and thick scapulo-humeral 
articulation ; it has a deep and narrow anterior notch, and. a shallow posterior emargi- 
nation. In a well-preserved specimen of the present species, in the Philosophical 
Institution, Birmingham, the length of the coracoid is 4 inches 5 lines, and the breadth 
3 inches ; the length of the humerus of the same specimen is 3 inches 10 lines, the 
breadth of its distal end is 3 inches. The transverse diameter of the radius equals the 
antero-posterior diameter of the centrums of two of the parallel vertebrae ; its anterior 
margin is notched. The ulna has a corresponding size, with a smaller anterior notch 
circumscribing with an apposed notch in the radius a roundish vacuity. These bones 
were anchylosed together and to the humerus in the Birmingham specimen. The 
' manus ^ commences by three transversely oval carpals, of which the radial one is 
notched, as in the radius ; but this character is not repeated, as in Ich. acutirostris and 
Ich. platyodon, in the next distal bone, nor is the radial digit bifurcate, as in Ich. com- 
munis and Ich. intermedins. There are but three series of digital bones, with a fourth 
shorter marginal series of smaller ossicles. 
In the hind paddle (PI. XXXII, fig, 6) the femur, like the humerus, has a longer 
shaft than usual, and not so proportionally broad a distal end. The tibia is notched 
anteriorly like the radius, but not so deeply ; the corresponding tarsal bone is more 
feebly emarginate. In this fin, also, there are but three series of digital ossicles. 
In the Museum of the British Institution there is a skeleton of Ich. tenuirostris 
thirteen feet in length : it is from the Lias of Lyme Regis, Dorsetshire. Evidences of 
the same species have also been obtained from the Lias of Stratford-on-Avon, of Bristol, 
of Street, Somersetshire, and at Barrow-on-Soar, Leicestershire. 
h . Ichthyosaurus longirostris, Oio. PI. XXV, fig. 2 ; PI. XXVIII, fig. 3 ; PI. 
XXXII, figs. 7, 8, 9. 
The specimens in the British Museum, from the Lias of Barrow-on-Soar, on which 
the present species is founded, and the least incomplete of which is the subject of figure 
