124 FOSSIL REPTILIA OF THE 



usual. Forty-five pairs of the 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 Ich. intermedins. Their 

 framework has fewer and larger bones, and the fore paddle impresses one with its massive 

 proportions compared with the vertebras. 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 

 humeral 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 vertebras ; 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. 



k. Ichthyosaurus longirostris, Ow. 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 



