76 BRITISH FOSSIL REPTILES. 



almost straight, truncate at each end, which very sHghtly exceeds in thickness the rest of 

 the bone. Each is about one fifth the length of the mandibular ramus. 



The coracoid (Tab. XXVII, fig. 7) shows a deep anterior notch, with only a feeble 

 concave outline at the corresponding part of the hind border of this bone. The clavicle 

 is applied and suturally attached to the lower half of the fore border of the scapula. 

 That border is nearly straight; the hinder one is concave through the backward pro- 

 duction of the thickened lower end to contribute to the articular surface for the humerus. 

 The anterior border of the radius and succeeding ossicle is emarginate. The chief 

 phalanges of but three digits are preserved in the subject of Tab. XXVII, fig. 4. The 

 character of the pectoral fin of the present species is probably rightly indicated in the 

 main; and in such essentially tridactyle character Ichthyosaurus lonchiodon may a^ree 

 with Ich. platyodon. 



The lower or distal ends of ischium and pubis seem to be equally expanded ; both 

 bones are broader than the ilium. The ventral fin has been dislocated and bent back- 

 ward close to the spine. The homotypal ossicles show the same emargination as in the 

 pectoral fin. 



The neural spines are relatively short (ib., fig. 6). 



This species has hitherto been found only at Lyme Regis ; it appears to be a rarer 

 Liassic Ichthyosaur than the three preceding ones. The skeleton above described was 

 discovered by Miss Mary Anning, to whom the discovery and extrication of many rare 

 and interesting fossils of the Lias of this locality are due. 



/. Ichthyosaurus longifrons, Oio. Tab. XIX, figs. 1 — 5 ; Tab. XX, fig. 1 ; Tab. XXI, 



fig. 1 ; Tab. XXII, fig. 1 ; Tab. XXIII, figs. 

 2—5. 



The characters of this species are those in which the subjects of the above plates and 

 of the general description of the cranial organisation of the genus differ in the specific 

 modifications referred to in other sections of the present Chapter. 



From the Upper Lias, with remains of Ammonites bifrons, of the Cotteswold Hills. 

 The more complete cranial specimen from the same Liassic zone at Curcy, Normandy, 

 has afforded the subjects of the figures in the plates above cited. 



g. IcHTHyosAUiius LATiFRONS, Koii. Tab. XIX, fig. C ; Tab. XXIII, fig. 1. 



In the year 1825 Mr. Konig, Keeper of the Department of Mineralogy, British 



