ii6 DICTIONARY OF BIRDS 



be allied, only rather more remotely, to the Turdidx — for Thrushes and 

 Chats are inseparable, and therefore this connexion must drag down the 

 Thrushes in the scale. Let it be granted that the more highly-developed 

 Thrushes have got rid of the low " Struthious " features whicli characterize 

 their Australian relatives, the unbroken series of connecting forms chains 

 them to the inferior position, and of itself disqualifies them from the rank 

 so fallaciously assigned to them. Nor does this consideration stand alone. 

 By submitting the Thrushes and allied groups of Chats and Warblers to 

 other tests we may try still more completely their claim to the position 

 to which they have been advanced. 



Without attaching too much importance to the systematic value which 

 the characters of the nervous system aftbrd, there can be little doubt that, 

 throughout the Animal Kingdom, where the nervous system is sufficiently 

 developed to produce a brain, the creatures possessing one are considerably 

 superior to those which have none. Consequently we may reasonably 

 infer that those which are the best furnished with a brain are superior to 

 those which are less well endowed in that respect, and that this inference 

 is reasonable is in accordance with the experience of every Physiologist, 

 Comparative Anatomist and Palaeontologist, who are agreed that, within 

 limits, the proportion which the brain bears to the spinal marrow in a 

 Vertebrate is a measure of that animal's morphological condition. These 

 preliminaries being beyond contradiction, it is clear that, if we had a series 

 of accurate weights and measurements of Birds' brains, it would go far to 

 help us in deciding many cases of disputed precedency, and especially such 

 a case as we now have under discussion. To the dispraise of Ornithoto- 

 mists this subject has never been properly investigated, and of late years 

 seems to have been wholly neglected. The lists given by Tiedemann 

 {Anat. und Naturgesch. der Vogel, i. pp. 18-22), based for the most part 

 on very ancient observations, are extremely meagre, and the practical 

 difficulties of carrying on further research, though not insuperable, are 

 considered to be great ; ^ but, so far as those observations go, their resvilt 

 is conclusive, for we find that in the Blackbird, Turdus merula, the pro- 

 portion which the brain bears to the body is lower than in any of the 

 eight species of Oscines there named, being as 1 is to 67. In the Red- 

 breast, Erithacns rubecula, certainly an ally of the Turdidse, it is as 1 to 

 32 ; while it is highest in two of the Finches — the Siskin, Garduelis 

 spinus, and the Canary-bird, Serinus canarius, being in each as 1 to 14. 

 The signification of these numbers needs no comment to be understood. 



Evidence of another kind may also be adduced in proof that the 

 high place hitherto commonly accorded to the Turdidse is undeserved. 

 Throughout the Class Aves it is observable that the young when first fledged 

 generally assume a spotted plumage of a peculiar character ^ — nearly each 

 of the body-feathers having a light-coloured spot at its tip — and this is 



^ One of the latest writers on the brain of Birds (Zeitschr. fur loissensch. Zoolog. 

 xxxviii. pp. 430-467, pis. xxiv. xxv.), though giving tables of the proportion of its 

 several parts in various genera, unfortunately gives none of the proportion of the 

 whole to the body. 



^ Blyth in 1833 seems to have indicated this well-known fact as affording a 

 character in classification {Field Nat. i. pp. 199. 200). Nearly 50 years after it was 

 claimed as the discovery of another writer. 



