I9I0.] SINCLAIR— DERMAL BONES OF PARAMYLODON. 



193 



Thin sections of the ossicles of Paramylodon were submitted to 

 Professor E. G. ConkHn who has kindly examined them and fur- 

 nished the following note : 



Histological Character of Dermal Bone, Horizontal and Vertical 

 Sections. — Penetrated by many canals for blood vessels, which, in general, 

 begin perpendicular to the surface but soon branch repeatedly and frequently 

 anastomose. Occasionally Haversian systems of lamellae and lacunae may be 

 seen around these canals, but generally these lamellae and lacunse are very 

 irregularly disposed between the canals. One of the most striking features 

 is the presence of bundles of fibres which run in all directions through the 

 bone, making the latter look almost like a woven fabric. These fibres are 

 most abundant in the spaces between Haversian systems. 



a 



Fig. I. Dermal ossicles of Paramylodon nebrascensis showing some of 

 the various forms assumed, a, irregularly shaped ossicle with transverse 

 groove; b, c, rectangular ossicle with groove toward one corner; d, another 

 rectangular bone with pyramidal surface; e, f, ossicles of irregular shape, 

 similar to some of those found overlying the scapula; g, h, ossicles of the 

 same character as those overlying the scapula; i, pitted ossicle, outer (?) 

 surface. All the figures are one and one half times the natural size. 



PROC. AMER. PHIL. SOC. , XLIX. I95 M, PRINTED JULY 27, I9IO. 



