CRETACEOUS FORMATIONS. 



51 



Fig. 4. 



Fig. a. 



Fig. 7. 



Fig. 5. 



/&■ .--"4- 





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v v \ 







1-1 



--'' y 



Proximal end and section of shaft of a metatarsal of Pohjptychodou ! 



Proximal end and section of shaft of a metatarsal of Pohjptychodon ! 



Of the detached metatarsals I subjoin outline sketches of the articular end, and the 

 transverse section of the shaft for facilitating the comprehension of their form and 

 their comparison with other remains. The chief of these is the proximal portion of a 

 metatarsal bone 15 inches, 6 lines in length. Figure 4 is the contour of the articular 

 end, which is slightly convex at the smaller side, nearly flat at the wider one, and 

 with a very irregular superficies, being pitted all over with depressions admitting the 

 end of the little finger, these depressions at some parts of the circumference of the 

 articular end being continued into as broad grooves, which soon subside to the level of 

 the surface of the shaft. Figure 5 is the outline of the fractured end, nine inches from 

 the articular end of the same bone : the angle indicates a ridge which runs obliquely 

 down the bone towards the middle of the surface, and subsides near the broken end, 

 fifteen inches down the shaft. The dotted line indicates the thickness of the laminated 

 wall, which gradually becomes less compact, and encloses a coarse cancellous structure. 

 The outer surface of the bone is smooth. 



Figure 6 gives the contour of the articular end of a proximal portion of a metatarsal 

 bone 1 1 inches long. The articular surface is pitted with cavities, as in fig. 4, the size 

 of the same, as if for a coarse ligamentous articulation : the cavities are continued 

 into grooves at b b. Figure 7 gives the contour of the broken surface, six inches 



