an almost perfect Skeleton of the Plesiosaurus. 387 



forms merely a short stem or handle (as it may be called) connected with the 

 transverse clavicles ; whereas in the plesiosaurus it is considerably more deve- 

 loped. The general analogies between these parts in the reptile tribe, in 

 the ornithorynchus, and in birds, have been ably pointed out by GeofFroy St. 

 Hilaire and Cuvier. 



In the plate containing a restoration of the plesiosaurus, I have added for 

 the purpose of comparison a sketch of this part in the ichthyosaurus. That 

 published in the Philosophical Transactions does not exhibit the tripartite 

 division of the furcula, and erroneously makes its branches curve considerably 

 too much upwards. The present outline is founded on three very perfect 

 specimens, which entirely agree with one another in the parts here repre- 

 sented, and leave no doubt of their actual form. 



Extremities. — The humerus articulates immediately with the bones which 

 in my preceding descriptions I had considered as the first row of the carpus ; 

 which contains only two instead of the three pieces placed together in the 

 conjectural restoration. I have again to acknowledge the error into which 

 I have been led in the insertion of a supposed radius and ulna between these 

 parts ; for the two pieces which form the first row formerly ascribed to the 

 carpus, now appear to be the true representatives of the radius and ulna, 

 though greatly differing in form from tlie usual type of those parts *. 



All the paddles are composed of two rows of nearly circular or discoidal 

 bones, representing the carpus and tarsus, and of five digitated series, re- 

 presenting the metacarpal or metatarsal and phalangic bones (the distinction 

 between these being inappreciable, though we may of course in conformity 

 to the usual nomenclature, term the first phalangic bones metacarpal, &c., if 

 so inclined. The first or anterior digit on each paddle has four phalanges ; 

 the last seven. These are evidently complete in the specimen ; the whole 

 five digits stand as follow : 



Posterior paddle. 

 4 phalanges. 



8, complete. 

 10, "1 uncertain whether 



9, J complete or not. 

 7, complete. 



This great multiplication of joints in the phalangic series strongly di- 





Anterior paddle. 





1st digit. 



4 phalanges. 



1st digit. 



2d .... 



7, and seems complete. 



2d .... 



3d .... 



7, incomplete. 



3d .... 



4th 



6, incomplete. 



4th 



5th ... . 



7, complete. 



5th .... 



* The conjectural restoration of the paddles would very nearly apply to the posterior paddles 

 as exhibited in this specimen, by abstracting the outer bone from this supposed carpus, and re- 

 moving also the exterior and circular bones from the edges of the paddle as there drawn. I was 

 led to introduce these exterior paddle-bones from the specimen represented fig. 1, PI. XLII., 

 Geological Transactions, Vol. V., in which they are so placed ; but I have subsequently re- 



