FISH-LIZARDS. 



251 



of the shoulder-girdle much resemble those of lizards, the collar-bones being well- 

 developed, and the T-shaped interclavicle resting on the lower surface of these and 

 the metacoracoids. The limbs are quite unlike those of any other reptiles, the 

 upper bone (humerus in the fore -limb) being very short and thick, while below 

 this the whole of the bones, as shown in the accompanying figure, were polygonal, 

 and so articulated with one another that the skeleton of the paddles assumed a 



SKELETON OP FISH-LIZARD, SHOWING YOUNG ONE WITHIN THE CAVITY OF THE RIBS (^ nat. size). 



(From Gaudry.) 



kind of pavement-like or mosaic structure. In most kinds the front paddles were 

 much larger than the hinder-pair ; and whereas, in some cases, two longitudinal 

 series of bones originate from the bone marked i in the accompanying figure, thus 



producing a very broad type of paddle, 

 in other forms (as shown in the skeleton 

 in the figure above), only a single series 

 articulated with that bone, and the whole 

 paddle was consequently much narrower. 

 Specimens like the one figured here show 

 that while the soft parts of the paddle 

 extended but a short distance in advance 

 of the front edge of the bones, on the 

 hinder -side they terminated in a wide 

 fringe, thus forming a structure admir- 

 ably adapted for swimming. Other 

 examples indicate that the back of these 

 reptiles was furnished with an upright 

 triangular fin somewhat like that of a 

 porpoise, behind which were a number 

 of small finlets, while the extremity of 

 the tail was expanded into a horizontal 

 fin, comparable to the flukes of a whale. 

 Many of these reptiles attained a length 

 of from 30 to 40 feet ; and they flourished throughout the whole of the Secondary 

 period, that is to say, from the epoch of the Trias, or Ked Sandstone, to that of the 



PART OF THE FORE -PADDLE OF A FISH-LIZARD. 



hu, bone of upper arm ; r.u, bones of fore-arm ; the 

 other letters indicate the bones of the wrist, below 

 which are the bones of the fingers. 



