SKIN AND REPRODUCTIVE ORGANS OF NOTORTGTES. 331 



over the modified ischiotergal patchy and in tlie pouch region. 

 The epidermis over the head region, i. e. behind the snout, 

 consists of at most three layers of cells, except at special 

 points (PI. 19, fig. 12). Here the epidermis is much thicker 

 (PI. 19, fig. 12, S.O.), having four or five layers of cells, 

 causing the Malpighian layer to become depressed into tbe 

 dermis, and the stratum corneum to become slightly raised. 

 Sometimes the whole structure resembles a raised platform, 

 often like a much-truncated cone in outline. In horizontal 

 diameter the top of the modified area varies from "11 mm. to 

 •15 mm. J while in vertical depth, excluding the corneous 

 layer, it is '04 mm. to '06 mm. The whole area of the 

 Malpighian layer involved may have a diameter of 2 mm. 

 The slightly larger examples were found in the ischiotergal 

 patch, though these structures are much more conspicuous in 

 the region of the head and neck, since there, as previously 

 stated, the whole normal Malpighian layer may be only "01 

 mm. thick. These structui*es are normally separated by a 

 space of 2"5 mm. 



The loose outer part of the corneous layer, which so 

 readily becomes detached elsewhere, tends to adhere more 

 firmly to the underlying part over these areas. The cells of 

 the Malpighian layer are much elongated and thinner, and, 

 in addition to sloping upwards and inwards, they are much 

 crowded horizontally. 



A tendency to become arranged around a central core is to 

 be noted in some cases. Their nuclei are also much elongated 

 and larger. In the modified ''ischiotergal" patch the whole 

 epidermis is, as previously stated, much thickened, but these 

 cutaneous structures are equally, if not more commonly, 

 developed there than in the skin of the head region. Over 

 the shoulder and thigh regions, as over most of the body, 

 these cutaneous organs do not appear to be present. The 

 structure is often pierced by a group of hairs, or it may be 

 flanked by such a group, while, on the other hand, they 

 would seem often to exist without any relation to hair- 

 groups. 



