126 



FOSSIL REPTILIA OF THE 



a score more for the wanting pinnigerous terminal portion of the tail, which probably 

 has been torn off by predatory assailants of the dead reptile. 



Besides the Liassic locality of Barrow-on-Soar, specimens and parts of Ichthyosaurus 

 longirostris occur in the zone characterised by jEgoceras angulatum ; also in the zone of 

 Arietiies Bucklandi? 



I. Ichthyosaurus latimanus, 2 Ow. PI. XXXIII, figs. 2, 7. 



This species is nearly allied to Ich. communis in the size and construction of the 

 pectoral paddle ; but the still smaller proportion of the pelvic one suggested the nomen 

 triviale, which is vindicated, also, as a sign of specific difference, by the proportionally 

 shorter and thicker jaws and by the modification of the vertebral centrums (PI. XXXIII, 

 figs. 2 and 7) ; in this character the present species differs from Ich. breviceps. 



Ich. latimanus resembles Ich. communis in the ventricose, subobtuse character of the 

 teeth, or, at least, some of the more worn ones, of the twenty-nine which may be counted 

 on each side of both jaws. The articular surfaces of the centrum are concave at the 

 middle third, the rest of the surface to the circumference is flat. 



In the specimen of Ich. latimanus, 6 feet 10 inches in length, and in that of an Ich. 

 communis, 5 feet 2 inches in length, the following were the respective dimensions of 

 bones of the scapular arch and its appendage : 



Scapula, length of . . 

 Coracoid, antero-posterior diameter 

 Coracoid, transverse diameter 

 Antibrachials, breadth of . 

 Length of fore fin, humerus inclusive 

 Breadth of ditto 



The clavicle is proportionally thicker than in Ich. communis; in the skeleton above 

 cited it is 6 inches 8 lines in length. 



The head is relatively shorter. In the specimen of which the dimensions are above 

 given the mandible is 1 foot 4 inches in length, while in the Ichthyosaurus communis 

 above compared it is 1 foot 5 inches in length. 



In a specimen of Ichthyosaurus latimanus in the Museum of the Philosophical Institu- 



1 See the classical Monograph, by Dr. Wright, F.R.S., &c, in the volumes of the Palaeontographical 

 Society issued in 18/8 and 18/9. 



2 'Report,' ut supra (1839), p. 123. 



Ich. latimanus. 



Ich. 



communis 



In. 



Lines. 



Tn. 



Lines. 



3 



4 



3 







3 



8 . 



2 



4 



3 



2 



.. 2 







2 



5 



.. 1 



7 



7 



6 . 



5 







3 



6 



2 



4 



