FROM THE LOWER LIAS OF CHARMOTJTH. 



459 



fracture, is scarcely, if at all, marked on the dorsal surface, is de- 

 fined in front by a curved line, which commences near the anterior 

 end of the scapular articulation, curves backwards to the middle of 

 its course, and then forwards till it ends against the inner margin of 

 the bone ; posteriorly it is defined by a line very slightly curved, 

 convex backwards, which commences from the hinder end of the 

 humeral articulation and passes very slightly backwards, also to end 

 against the inner margin. From this ridge the bone thins rapidly 

 away in front and behind, more rapidly in front, till it ends in a 

 thin edge. 



The posterior region of the right coracoid is traversed by several 

 lines of fracture, on one side of which the surface of the bone remains 

 higher than on the other, and thus forms little cliffs. A broken sur- 

 face, dividing the bone across, reveals its internal structure, and shows 

 between its dense outer layers a more cancellous open tissue in the 

 middle ; not only so, but in some places the middle of the bone is 

 occupied by a layer of calcite ; and this is thicker on that side of a 

 fracture where the surface is higher, and thinner on that side where 

 it is lower. This calcitic layer is probably due to the replacement 

 of cartilage ; and it is thinner where the bone is thinner on the side 

 of a crack, because the cartilage had there been squeezed together by 

 pressure of overlying strata. 



The measurements of the right coracoid are given below : — 



inches. 



Maximum length (fig. 4, mx) 17*375 



Length of harmonia (ib. a p) 10*5 



Breadth (ib. tr) 8-6 



Breadth along median ridge (ib. h r) 8*0 



Distance from anterior end of coracoid to 



posterior edge of glenoid cavity (ib. mi). . 10*0 

 Length of chord of anterior concave margin 



of coracoid (ib. md) 2'75 



Height of arc of anterior concave margin of 



coracoid (ib./) 0-375 



Length of articulation for the scapula (ib. d s) 3*3 



Length of articulation for the humerus (ib. st) 3*2 



Thickness at articulation for the humerus. . 1*6 

 Length of chord of posterior and outer lateral 



curve (ib. tz) 8*3 



Height of arc of posterior and outer lateral 



curve (ib. n) 2-3 



Length of chord of posterior convex margin 



(ib. zp) 7-5 



Height of arc of posterior convex margin 



(ib. o) 3-3 



Thickness of median ridge where broken in 



middle of its course (left coracoid) 0-91 



Thickness of anterior region of coracoid. . . . 0-25 



Thickness of posterior region of coracoid . . 0*6 



