BRITISH FOSSIL RKPTILES, 111 



The iliac bones are situated opposite the 44th and 45th verte- 

 brae, both which have the two costal tubercles distinct. These 

 become blended into a single oblong oblique surface at the 48th 

 vertebra : this surface is situated as usual near the anterior and 

 lower margin of the centrum. A space equal to one diameter 

 and a half of the costal pit intervenes between them and the 

 neurapophysial surfaces. 



In a skeleton in Mr. Hawkins's collection there are 126 verte- 

 brae. The two costal pits become blended at the 48th vertebra ; 

 the single tubercle disappears at the 76th vertebra, where the 

 bend of the tail commences. Here three or four of the ver- 

 tebrae are more compressed in the antero-posterior direction 

 than those that immediately precede and follow them. The ribs 

 are slender, and become flattened and longitudinally grooved at 

 their distal extremities. They become straight, short, and like 

 transverse processes after the 42nd pair. 



There are 103 vertebrae in Mr. Johnson's fine skeleton of this 

 species from Charmouth, but the series is not complete. In a 

 beautiful skeleton of the Icfi. intermedius from the lias of Lyme 

 Regis, in the collection of Miss Conybeare, the tail exhibits 

 the usual fracture or bend, which takes place at the 78th ver- 

 tebra. 



In the lower jaw the surangular is continued further forwards 

 than the angular, before it is overlapped by the dentary ; but 

 this is not continued so far forwards as in the Ich. communis. 



The surangular bone presents a longitudinal notch on its out- 

 side, which begins a little anterior to the articular cavity, and 

 becomes gradually shallower as it advances forwards. The 

 length of the lower jaw is to that of the vertebral column as 

 3 to 11. 



In a small specimen of Ich. intermedhis in Lord Cole's col- 

 lection in which the upper maxillary bone measured 2 inches 8 

 lines, the diameter of the eye-plates was 2 inches, and that of 

 the pupillary space 1 inch. I count 17 sclerotic plates. 



The transverse portion of the episternum is rather longer and 

 thicker than the median longitudinal piece. 



The clavicles are very long and strong, especially at the 

 middle ; they are concave at their inner surface. 



In the coracoid bone the humero-scapular articulation is of 

 less extent than usual; the upper notch is as long and not 

 deeper than the lower one ; so that the neck of the scapulo- 

 humeral articulation is longer than in the Ich. platyodon or 

 tenuirostris. 



The radial margin of the scapula is straight; the outer sur- 

 face at the expanded humeral end is slightly excavated. 



