STRUCTURE OF PLESIOSAURIAN PROPODIAL 



405 



fig. 5), the characters of which liave ah-eady been fully de- 

 scribed (Williston '03 and Moodie '11). In this specimen all of 

 the growth characters above referred to, i.e., canal, foramen, 

 cavity and groove, are present. The groove forms, save for 

 a slight interruption, a shallow smooth-bottomed trough en- 



u» 



0: 

 1 



I 



rorameo 



Fig. 3 A drawing of the edge of a plesiosaurian (Polycotylus) propodial 

 showing the growth characters in the shape of a groove at the distal end and 

 three foramina which later may have cither developed into Volkmann's canals or 

 have disappeared. 



Fig. 4 Drawing of the cross-section of the femur (fig. 1) as it is shown in 

 a broken condition in plate 1, figure 3. The foramen is the same as one of those 

 shown in figure 3. 



