U5(; THE SENSE OF TOUCH IN ANIMALS 



Among Insectivores the low development of the skin of the 

 Mole, Fig. 113, is noteworthy, and is correlated with the rough 

 digging-work required of the forefeet of this animal, and the 

 special arrangements subserving the sense of touch which 

 reside in the snout. The Hedgehog shows little differentiation 

 of the elements of the skin {see Figs. 114, 115). 



The only specimen from the Chiroptera, Fig. 116, is indicative 

 of high development of the papillae of the corium, and little 

 modification of the epidermis. The Lemuridce, Lemur hrunneus, 

 Figs. 117, 118, 119, 120, 121, 122 ; Lemur mungoz, Fig. 125 ; 

 Lemur catta, Fig. 126 ; Galago crassicaudata, Fig. 127 ; Nycti- 

 cebus tardigradus and Javanicus, Figs. 128, 129, are a striking 

 group illustrating the fact that the lowest of the Primates 

 are much above any of their known ancestors, or animals below 

 them in the zoological scale. This group will be more particu- 

 larly referred to in the physiological section. From this group 

 onwards papillary ridges and papillae of the corium become 

 variously modified, but are always present in a high degree, as in 

 Hapalidce, Figs. 132, 131, 130 ; Papio, 135, 139 ; Cercopithecidce, 

 Figs. 142, 148; Hijlobatidoe, Figs. 150 to 153; Simia satyrus. 

 Figs. 154 to 157 ; Antropopithecus troglodytes, Figs. 158, 159, 160. 

 In many of these special modifications and adaptations are 

 seen. In Man the structures of the skin hardly show higher 

 development than in many lower Primates, though the papillary 

 ridges often imbricated in hand and foot, and the papillae of 

 the corium, as in Figs. 164, 161, 162, 165, are exceedingly well 

 developed. Fig. 161 shows well the large compound papillae 

 of the corium at the tip of the fourth digit. 



The eight birds shown have no elaborate epidermic modifica- 

 tions, but some very interesting arrangements of the papillae 

 of the corium, and imbrication of the scales (Figs. 166 to 

 173). 



(2) This rule is illustrated throughout the series, even as 

 low as Didelphjs, Figs. 55, 54, where marked papillary ridges 

 and papillae of the corium go together, and obtains through 

 the various groups, especially the Primates up to Man. The 

 point may be best illustrated by referring to those cases where 



