192 SINCLAIR— DERMAL BONES OF PARAMYLODON. [April 22, 



resembling that of a mylodont was found partly exposed, with a row of small 

 ossicles immediately over the outer side. The section of the bed containing 

 these bones has recently been worked out, and the row of small bones proves 

 to be the edge of a distinct layer including between 250 and 300 individuals. 

 They mantle over the outer surface of the scapula, being removed from it by 

 about an inch of asphalt. 



The layer of bones as we find it has probably been disturbed somewhat 

 and does not occupy its original position exactly, but the fact that it remains 

 as a distinct layer with a tendency toward similar orientation of the individual 

 ossicles indicates that the disturbance has not been great. As the position 

 of the layer in the asphalt was nearly vertical, the presence of the large 

 number of ossicles together may not be attributed to the washing together of 

 scattered elements on the floor of a small basin of deposition. 



The ossicles are not closely pressed together and are not superimposed. 

 The individuals range in size from a cross-section of 6.5X4-5 n^rn- to 

 21X16 mm. Excepting a few of the largest ones, which are nearly square, 

 the greater number are rounded and rather irregular in form. The outer 

 side is in some cases more regularly modeled than the inner. The surface 

 of the bones is somewhat roughened or pitted in some instances, but no 

 markings are present which would be considered as definite sculpturing. The 

 microscopic structure has not yet been examined. 



In general the form, size and arrangement of the ossicles are much as 

 in the bones in the Grypotherium skin from Patagonia. The skin fragment 

 first described by Woodward was thought to represent mainly the region of 

 the neck and shoulder. The Californian specimen mantles over the outer 

 side of the scapula, and is presumably not far removed from its original 

 position with relation to this bone. 



Subsequent investigation has added little to this, so far as the 

 localization of particular types of ossicles is concerned. Some 

 idea of the diversity of forms assumed by them may be gathered 

 from the accompanying figure, in which several of the types men- 

 tioned in the citation may be recognized (especially in Fig. i, 

 b, c, d, g and h), nor do these differ essentially from the great mass 

 of scattered and unlocated ossicles. Pitted and smooth forms 

 occur in the same individual. In some of the bones, except for 

 minor undulations and the pores for the entrance of blood vessels, 

 the outer surfaces are smooth and polished (Fig. i, e, f). Others 

 show a highly irregular pattern of small anastomosing ridges (Fig. 

 I, h), but, as previously noted, there is no constancy or regularity 

 in the pattern. Grooves cut across some of the ossicles, as shown in 

 the figure. Some of these may be due to the fusion of two 

 adjacent elements, as suggested by Woodward for the origin of a 

 similar structure in Grypotherium. 



