DAY AND NIGHT 29 



many of the arboreal Lemurs, the most primitive 

 of the order Primates, are strictly nocturnal and 

 hence cryptotactic. Burrowing mammals are 

 generally nocturnal as well, including the egg- 

 laying mammals of Australia, the scaly ant-eaters, 

 ground-porcupines, and others too numerous to 

 mention ; the combination of fossorial with diurnal 

 habits is rare, the common rabbit affording an 

 instance of it. Others resort during the daytime 

 to ready-made holes, hollow trees and caves, as 

 the dasyures, mungooses, and sloth-bears. Some 

 species exhibit mixed habits ; but the cryptotactic 

 tendency is universal amongst mammals. 



It is not possible to tabulate lists of phaner- 

 ozoa and cryptozoa, because all animals have 

 cryptozoic potentialities. Those that are not 

 definitely cryptotactic have the power of retreat- 

 ing to cover at the sign of danger ; or of causing 

 the aggressor to vanish from the scene by reason 

 of their weapons of offence. The scent-glands 

 of the mephitic skunk, of the naked bat {Chiro- 

 meles), and in a lesser degree of the civet cats, 

 are cryptotactic organs of a virulent type not- 

 withstanding that they effect their object through 

 the olfactory sense ; besides being protected by 

 their secretions, these animals are nocturnal. 

 Scorpions, centipedes, and poisonous snakes are 

 cryptozoic as well as armed for attack, so that 

 they also are doubly protected and doubly 

 dreaded by their enemies. 



