BRITISH FOSSIL REPTILKS. 121 



part of the cnemial than of the tarsal series ; this latter row of 

 three bones bein^ completed by the intercalation, in its middle, 

 of an ossicle which forms part of the third or metatarsal row in 

 the intermedius and communis. The character above noticed 

 in the temiirostris may be observed, in a slighter degree, in the 

 Ich. platyodon. 



Size. — In the museum of the Bristol Institution there is a 

 magnificent though not complete skeleton of the Ich. temii- 

 rostris, which measures thirteen feet in length. In Mr. John- 

 son's private collection, in the same city, there is a lower jaw 

 of the Ich. temiirostris from Lyme Regis, which measures two 

 feet six inches in length : the exserted crown of one of the 

 largest teeth in this specimen measures one inch and a half in 

 length, and four lines in diameter across the base. 



Localities. — The skeleton in the Bristol Museum is from the 

 lias at Lyme Regis, where the species appears to be, however, 

 less common than the Ich. communis and jilatyodon. The in- 

 complete specimen from the lias of Stratford-on-Avon, in the 

 museum of the Geological Society of London, and described by 

 Mr. Sharpe under the name of Ichthyosciurus grandipes, belongs 

 to the present species. Lord Cole possesses some characteristic 

 fragments from the lias in the neighbourhood of Bristol. 

 Evidences of the Ich. tenuirostris have been procured at Street 

 and Walton, and at Barrow-on-Soar, in Leicestershire*. 



This species undoubtedly exists in the lias formations of Boll 

 and Amburg, in Wirtembergf, and in the Jura limestone near 

 Solothurn. 



Ichthyosaurus acutirostris. 



Under this name is indicated a species of Ichthyosaurus, 

 which appears to be more common in the lias formations of the 

 neighbourhood of Whitby than in those of Dorsetshire, although 

 specimens also occur in the lias quarries of Street and Walton. 



The teeth of the Ich. acutirostris, when they occur sepa- 

 rately and singly, are hardly distinguishable from those of the 



* Professor Sedgwick has an incomplete skeleton of the Ich. tenuirostris from 

 this localit}', in which the tail presents the abrupt and characteristic bend so 

 common in the present genus ; three of the ribs also of this interesting specimen 

 have been fractured during the lifetime of the animal, and the fractured ends are 

 rounded and expanded,andit is evident, that afalsejoint has been formed; theun- 

 intcrmittingrespiratory movements havingprevented acomplete osseous reunion. 



f The skeleton of the Ich. tenuirostris in the Gymnasium of VVirtemberg is 

 in some respects more complete than are any of those yet preserved in the 

 museums of this country, not excepting the beautiful specimen in the museum 

 of the Philosophical Institution of Birmingham. It is well described and 

 figured by Professor Jjiger, in his treatise " De Ichthyosaiu'i Fossilis Speci- 

 minibus," fol. 1824, and has enabled me to ascertain the number of ribs which 

 surround the thoracic-abdominal cavity, and at the same time test the con- 

 stancy of the character derived from the form of the humerus and the emargi- 

 nation of the anterior edge of the radius and tibia. 



