70 BRITISH FOSSIL REPTILES. 



notch deeper than the posterior one (Tab. XXVI, fig. 3). The clavicles are long and 

 strong, applied, as usual, to the fore border of the transverse rays of the episternum and 

 to that of the scapulse. 



The bones of both fore and hind paddles have afforded the description given in the 

 preliminary general account of the Ichthyosaurian skeleton (p. 62). 



In the specimen (Tab. XXVI, fig. 3), in which the pelvic arch and limb are unusually 

 well preserved, the ilium (ib. figs. 5, 62) is sabre-shaped or moderately curved backwards ; 

 in length 2} inches, with a breadth of 5 lines at the middle. The pubis (64) of the same 

 pelvis is 2 inches 9 lines in length, 1 inch in distal breadth ; both fore and hind borders 

 are concave. The ischium (63) is nearly of the same length as the pubis, with a distal 

 breadth of 9 lines, and a deeper concavity of the anterior border. The entire vertical 

 extent of the pelvis is 5 inches. 



The length of the pelvic paddle in the subject of fig. 1, Tab. XXIV, is 4| inches; 

 that of the femur being 1 inch 7 lines. The extreme breadth of the paddle is 1 inch 

 10 lines. At this part there are five phalanges in transverse line, that number occurring 

 at the fifth bone from the femur. The midtarsal encroaches further between the tibia 

 and fibula than usual. 



The Ichthyosaurus communis occurs chiefly in the Lias of Lyme Regis and Charmouth, 

 Dorsetshire ; in that of Street, Somersetshire, it is rarer than the Ichthyosaurus inter- 

 meclius. Remains of Ichthyosaurus comvmnis have been met with in the Lias near 

 Bristol. This species is associated with Ich. intermedius and Ich. tenuirostris in the Lias 

 of Barrow-on-Soar ; it occurs, likewise, in the same formation at Stratford-on-Avou. 

 In all these localities Ammonites of the species Arietites BucMandi have been associated 

 with the Ichthyosaurian fossils. 



c. Ichthyosaurus intermedius, Ch. (Tab. XX. fig. 7, Tab. XXVI, figs. 1 and 2). 



In this species the orbits are of moderate size,^ and the facial portion of the skull in 

 advance equals in length about three times the antero-posterior diameter of the orbital 

 outlet. The teeth (Plate XXIV, fig. 7) are relatively smaller and longer than in Ich. com- 

 munis (ib., figs. 5, 5') ; the crown has a narrower base, is more acutely conical, with finer 

 longitudinal strias, and the root has less prominent ridges. The number of teeth is from 

 thirty-five to forty on each side of both upper and lower jaws. 



The entire length of the skeleton is from five to five and a half times that of the 

 mandible. 



In the best preserved specimens the number of vertebrae ranges between 130 and 

 140. In the space between the scapula and pelvic arches there are about forty vertebrae, 



^ Compare with fig. 3, Tab. XXIV, Ichthyosaurus longirostris. 



