DERM OF MAMMALIA. 6 11 



fibrocartilage ; but its attachment along the median line of the 

 fore part of the head was so firm as to require, especially beneath 

 the horn, the use of a chisel in order to separate it from the skull. 



Besides its attachment to subcutaneous cellular substance, fasciae, 

 elastic tissue, fibro-cartilages, and periosteum, the derm is con- 

 nected with parts which are destined for its motions and adjustment 

 upon the body. The ' panniculus carnosus ' of the Rhinoceros is 

 developed in certain parts to an extraordinary thickness ; the 

 permanent folds in the hide of the Indian species serving to afford, 

 like the processes of bone, a firmer insertion to the aponeuroses 

 of the cutaneous muscles than a plane surface of integument could 

 have done. A sheet of these muscles situated on each side of the 

 thoracic or scapular region sends its fascia into the interstice of 

 the fold in front of the anterior extremities, the skin being bent 

 upon itself, as it were, to grasp this fascia. Similar portions of 

 panniculus carnosus send their aponeuroses into the posterior 

 folds of the skin. 



The derm, in Cetacea, is a somewhat gradual condensation of 

 the close fibrous reticulation in the areolae of which the oil is con- 

 tained; the thickness of such subcutaneous tissue, called ' blubber,' 

 beinff enormous in the large Whales : it is wanting at the fins, 

 and here the derm is closely connected with the sclerous tissue 

 covering the bony framework of the pectorals, and contributing 

 mainly to form the dorsal and caudal fins : in the latter the sub- 

 dermal fibres become assorted into three layers, the upper and 

 under ones being longitudinal, the intermediate layer transverse, 

 and the texture of the whole so compact that the traversing veins 

 as well as the arteries preserve their open state when cut across. 

 The fine lengthened papillae or villi from the periphery of the 

 derm are noticed at p. 188. 



Certain Rodentia contrast with the Pachyderms in the thinness 

 and lacerability of their derm, resembling birds in that respect. 

 Another Lissencephalous family reproduces a crocodilian cha- 

 racter, in the development of osseous scutes upon the peripheral 

 part of the derm (vol. ii. p. 396, fig. 261). These scutes are 

 small, mostly quadrilateral, and suturally united so as to form 

 three principal groups : one protecting the trunk like an arched 

 roof, a second forming a flatter shield or helm upon the head, the 

 third encasing the tail, like a sheath. In most existing Armadillos 

 the trunk-armour consists of an anterior thoracic buckler in which 

 the ossicles form a kind of mosaic work ; a middle ' annular ' part 

 in which they are disposed in transverse series movable upon 

 each other ; and a posterior lumbar buckler, like the thoracic 



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