150 DE. r, p. MORENO AND MB. A. S. WOODWARD ON [Feb. 21, 



and all are remai'kablj 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. E.. 

 H. Burue has kindly made some trans\'erse sections, which prove 

 the hairs, to be almost or quite cylindrical, and none of the speci- 

 mens 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 t'peciraen, even in the compara- 

 tively thin region near the supposed ear. They form everywhere 

 a very compact armour, and some of 1 hem are quite closely pressed 

 together ; rarely, indeed, there is a shallow groove crossing a speci- 

 men, possibly indicating two components which were originally 

 separate. As sho«n by every part of the cut margin, and especially 

 well in a small section prepared by Prof. Charles IStewart (PL XV. 

 fig. 1), 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 (e. g. around G in Pi. XIV.), 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 indiscriminately 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 sha])e 

 when viewed from within, and measure approximately O'OIS m. by 

 0*010 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 Aihich have been examined is slightly convex, more 

 or less flattened, without any trace of regular markings (PI. XV. 

 figs. 2,3). _ 



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 IStewart. A 

 portion of a horizontal section is shown enlarged about 40 times 

 in PI. XV. fig. 7 ; and one of the Haversian systems from its 

 middle area is represented, much more highly magnified, in fig. 7 a. 

 The tissue is traversed in all directions by a dense mass of intei'- 

 lacing 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 may be observed to radiate 

 regularly outwards. Numerous small vascular canals, frequently 

 branching, are cut in various directions ; and the bony tissue, 

 which is de^'eloped in every part of the ossicle, exhibits abundant 



