14 POSSIL REPTILIA OF THE 



In Alligator lucius the trunk from the third cervical to the last sacral vertebra inclusive 

 is nearly equal to two lengths of the skull ; the length of the tail is 2^ lengths of the 

 skull. The trunk of Theriosuchus so defined includes two lengths of the skull. The 

 tail, as indicated by fig. 2, PL IV, equalled 2^ lengths of the skull. 



In the long-jawed Gavials and Teleosaurs the trunk includes about 1^ length of 

 the skull ; but the tail is proportionally longer than in the short- and thick-jawed 

 Crocodiles. 



Crocodilian vertebra. Plate I, figs. 4 — 12. 



Of the numerous scattered vertebrae in the diSerent slabs of the Purbeck matrix 

 those specimens have been selected for figuring which exemplify the Crocodilian 

 characters of different portions of the vertebral column. 



The subject of fig. 4, PI. I, is from the neck or fore part of the trunk, in which 

 the hypapophysis {hy) has not subsided on the under surface of the centrum ; the 

 processes for the head (' parapophysis,' p) and tubercle (' diapophysis,' d) of the proxi- 

 mally bifurcate rib are well developed. The pre- (=) and post- (z') zygapophyses, 

 together with the neural spine ("•*•), complete the series of developments of this complex 

 type of Crocodilian vertebra.^ 



Pigs. 5 and are two consecutive, but slightly dislocated, vertebrae from the hinder 

 part of the trunk. The long and broad diapophyses show the notch {d) where the 

 simple and short hinder ribs were articulated, each by a single joint, with the rest of 

 their osseous ' segment ' or vertebra.^ 



Pigs. 7 and 8 are side views of mutilated hinder trunk vertebrae. 



Pig. 9 gives a back view of one of the sacral vertebrae, showing the robust processes 

 represented by coalesced pleurapophyses. The suture is traceable by which the latter 

 articulate with both centrum and neural arch.^ 



Pig. 10 is a caudal vertebra, with the haemal arch and spine {h) ; a front view of the 

 latter is given in fig. 11 ; the vertebra is from that part of the tail where the pleura- 

 pophyses cease to be developed.* 



Pig. 12 shows the completely ossified substance in a section of a dorsal centrum. 



Pig. 13 probably belonged to Brachi/dectes minor. 



All these and other detached vertebrae indicate the dwarfed proportions of the 

 Crocodilia characteristic of the fresh-water deposits of the ' Peather-bed.' Many 



^ No. 087, Osteological Catalogue, 1853. 



" No. 689, op. cit., p. 153. 



^ It accords with the character of the sixth cervical vertebra in Gavialis gangeticus (' Catal. of 

 Osteology, Mus. Coll. Chir.,' 4to, vol. i, p. 152, No. 684), save in the minor devolopment of the 

 hypapophysis, which indicates a position in the vertebral column somewhat further back. 



4 



See No. 086 of the same series and * Catalogue,' loc. cit. 



