3o8 THROUGH THE HEART OF PATAGONIA 



length, those at the hinder (lower) border about the same ; while some of 

 the comparatively small and delicate hairs on the supposed cheek are not 

 longer than o.oi m. The hairs are stiff, straight, or only very slightly 

 wavy, and all are remarkably tough. Examined under the microscope, 

 their cuticle is observed to be quite smooth, while the much-elongated 

 cells of the cortex are readily distinguishable. Mr. R. H. Burne has 

 kindly made some transverse sections, which prove the hairs to be 

 almost or quite cylindrical, and none of the specimens examined present 

 any trace of a medulla. 



The dermal ossicles are very irregular in arrangement, but are to be 

 observed in every part of the specimen, even in the comparatively thin 

 region near the supposed ear. They form everywhere a very compact 

 armour, and some of them are quite closely pressed together ; rarely, 

 indeed, there is a shallow groove crossing a specimen, possibly indicating 

 two components which were originally separate. As shown by every part 

 of the cut margin, and especially well in a small section prepared by 

 Prof Charles Stewart, they are all confined to the lower half of the 

 dermis, never encroaching upon the upper portion in which the hair is 

 implanted. It is also to be observed that, where the inner surface of 

 the skin is intact, the ossicles are completely embedded and only faintly 

 visible through the dry tissue. The exposure of a considerable number 

 of them, as already mentioned, is due to the rupture and partial abrasion 

 of this surface. No tendency to arrangement in parallel lines or bands 

 can be detected ; and large and small ossicles seem to be indis- 

 criminately mingled, although of course allowance must be made, in 

 examining sections and the abraded inner view of the skin, for differences 

 in the plane of adjoining sections and varying degrees of exposure 

 by the removal of the soft tissue. The largest ossicles are oblong in 

 shape when viewed from within, and measure approximately 0.015 m. 

 by 0.0 10 m. ; but the majority are much smaller than these. They are 

 very variable and irregular in form ; but their inner face is generally 

 convex, sometimes almost pyramidal, while the outer face of the few 

 which have been examined is slightly convex, more or less flattened, 

 without any trace of regular markings. 



In microscopical structure the dermal ossicles are of much interest, 

 and I have examined both horizontal and vertical sections, one of the 

 former kindly prepared by Prof Charles Stewart. The tissue is traversed 

 in all directions by a dense mass of interlacing bundles of connective- 

 tissue fibres, which exhibit an entirely irregular disposition, except quite 

 at the periphery of the ossicle. Here they are less dense, and are 

 arranged in such a manner as to form at least one darkened zone 

 concentric with the margin in the comparatively translucent border. 

 Occasionally, but not at all points, the fibres in this peripheral area 



