PuBNELL. — The Animal and Human Mind compared. 77 



upon successive generations experiencing the same conditions 

 of life. If an ancient type is suited to its surrounding con- 

 ditions, and those conditions remain unchanged, while the 

 animal is able to protect itself against enemies, the type may 

 remain unchanged for an indefinite length of time. This is 

 well seen in the case of some marine brachiopods. Thus 

 the genera Lingula and Discina, which are still abundant in 

 modern seas, are also found in the Cambrian rocks, and the 

 Cambrian forms are practically undistinguishable from the 

 modern. So the genus Tcrcbratula, which first appeared in 

 the Devonian formation, is still extant. Other instances 

 might be quoted, the interpretation of the extraordinary 

 persistence of such types, compared with the rise and fall of 

 others, being, I believe, due to the fact that these particular 

 forms of life have never been subjected to the unfavourable 

 changes in the environment which other forms have been 

 required to meet, and to which the latter have succumbed. 

 We may fairly assume that the mind of the Lingula, like its 

 body, has remained practically unaltered since the Cambrian 

 epoch. M.any millions of years have elapsed, but the race has 

 neither progressed nor retrograded, whether in body or in mind. 

 Other creatures, however, have been forced into severer 

 struggles for existence ; new bodily forms have thus been 

 evolved, and fresh mental developments taken place. Stores 

 of inherited memories have been accumulated, and fresh mental 

 capacities evolved. The minds of different orders of animals 

 have followed different lines of development, just as their 

 bodies have done. The starling and the worm which it 

 captures may owe their origin to a common ancestor in the 

 far distant past ; but how unlike their bodily structure, and 

 how different must be their mental organization ! It would 

 seem as if the various orders of animals had their broad 

 mental specialities, although our present knowledge of the 

 subject is too vague to enable us to fully comprehend those 

 specialities. To illustrate my meaning I will refer to the de- 

 velopment of the aesthetic sense in birds. That birds take 

 extreme pleasure in singing is manifest. Their songs are 

 more than ebullitions of overflowing spirits. Birds evi- 

 dently appreciate each other's vocal efforts. The male 

 bird frequently sings to the female while the latter is incu- 

 bating. The New Zealand saddleback, which is naturally 

 a noisy bird, is one of them. Sir Walter Buller says that 

 during the breeding season the male performs to his 

 mate in a soft tone of exquisite sweetness. The plea- 

 sure, however, which the female derives from these dis- 

 plays must be regarded as more of a sensual than of an intel- 

 lectual nature ; but many birds seem to rejoice in singing 

 for its own sake, and to be able to criticize the excellence 



