IIG REPORT— 1839. 



responding bone of the fore extremity, and the same character 

 occurs in the tM^o succeeding ossicles forming the anterior mar- 

 gin of the paddle. 



The middle bone of the first or tarsal row is distinguished by 

 a wedge-like process at its upper margin, which fits into the 

 interspace of the tibia and fibula. There are three principal 

 digital series as in the fore paddle, but the supplementary row 

 contains a greater number of ossicles, and is situated on the 

 posterior instead of the anterior side of the paddle. 



The anterior digital series includes, counting from the tibia, 

 nine ossicles, the median row eleven, and the posterior ten os- 

 sicles : there are eight small ossicles in the posterior rudimental 

 digit. 



Besides the comparative fewness of the digital ossicles in the 

 paddle of the present gigantic species, they are characterized by 

 their being placed at greater distances from each other in the 

 terminal or lower half of the paddle, indicating that the liga- 

 mentous substance which connected them together entered more 

 abundantly into the formation of the fin. 



The imperfect spinal column, including 110 vertebrae, of an 

 Ich. idatyodon from Lyme, now in the British Museum, mea- 

 sures eighteen feet in length : but portions of the skeleton of the 

 Ichthyosaurus 'platyodon^ as the magnificent fragment of the 

 cranium in possession of Mr. Johnson of Bristol for instance, 

 have been discovered, which indicate individuals exceeding thirty 

 feet in length. 



Localities. — The lias of the valley of Lyme is the chief de- 

 pository of this gigantic species, but its remains are pretty widely 

 distributed : they have been found in the lias of Glastonbury, 

 of Bristol, of Scarborough and Whitby, and of Bitton in Glou- 

 cestershire. 



Vertebrae of this species occur in the lias at Ohmden, but not, 



apparently, at Boll, where the Ich. communis and temm^ostris 



occur : at least, the specimens referred, doubtfully, by Prof. Jager 



to the Ich. lilatyodon have the characters of the Ich. communis. 



Ichthyosaurus lonchiodon, O.* 



A magnificent specimen of this species, measuring upwards 

 of 15 feet, formed part of the second collection of Saurian re- 

 mains purchased by Parliament of Mr. Hawkins, and now de- 

 posited in the British Museum. 



The head somewhat exceeds, in relative size, that of the Ich. 

 plati/odon, to which the present species is closely allied : the 

 jaws are deeper, and taper less gradually to their extremities. 

 The teeth are more slender in proportion to their length than in 

 the Ich. communis or platyodon, and are straighter than in the 

 tenuirostris or intermedius. Their base is cylindrical, and re- 



* y^O'/x'^' ^ifsfc, olov;, dens. 



