16 THE SENSE OF TOUCH IN ANIMALS 



It may be noted that all these belong to the order of Carnivores 

 except the Tasmanian wolf, a marsupial with many features 

 resembling the Carnivores. 



(7) Papillary ridges only reach their full development in the 

 Primates, and thirty species of these have been examined, 

 in which the whole of the palmar and plantar surfaces are 

 covered with ridges and their intervening furrows. The thirty 

 species are : Hapale jacchus, Midas ursulus, Papio mormon, 

 Papio cynocephalus, Papio porcarius, Papio hamadryas, Papio 

 bahouini, Cijnopithecus niger, Chrysothrix sciurea, Cebus 

 fatuellus, Macacus cynomologus, Macacus nemistrinus, Macacus 

 pileatus, Macacus inuus, Macacus silenus, Cercopithecus ruber, 

 Cercopithecus callitrichus, Cercopithecus diana, Cercopithecus 

 lalandi, Cercopithecus campbelli, Cercopithecus cynosurus, Cerco- 

 cebus cethiops, Cercocebus collaris, Cercocebus hagenbecki, Hylo- 

 bates lar, Hylobates hainanus, Hylobates hoolock, Simia satyrus, 

 Anthropopithecus troglodytes, Gorilla savagei. 



Besides these representatives of the main groups of Primates, 

 it is probable that every species of this order, if examined, 

 would show this particular modification of the Primates, and 

 that it is a character of ordinal rank. Of course its highest 

 development is found in the hand and foot of man. 



Of the four mixed types A is the simplest, the epidermis 

 being corrugated in var5dng degrees, and the digits furnished 

 with coarse tranverse ridges. There are four forms which 

 present this modification : Mus decumanus, Mus musculus 

 (the brown rat and house mouse), Arvicola amphibius, and 

 Arctomys marmotta. No similar modification has been found 

 outside the Rodent order. 



B. — Corrugated epidermis covering the greater part of the 

 palmar and plantar surfaces, but showing locahsed small groups 

 of papillary ridges on certain of the pads (digital palmar or 

 plantar). Petaurus sciureus, Sciurus vulgaris, Sciurus prevosti, 

 Sciurus cinereus, Cercoleptes caudivolvulus, Lutra vulgaris, and 

 Erinaceus europorus are the forms found with this particular 

 arrangement. 



C. — Nodules associated with papillary ridges are characteristic 



