NOTES ON INDIAN TIMELIIBE8 AND THEIR ALLIES. 45 



The Timeliides as above constituted are strictly non-migratory 

 and very sedentary in their habits, living the whole year round 

 practically in the same locality.* They have no distinctive summer 

 and winter plumage, which at once separates them from the 

 Warblers. Very little appears to be recorded about the plumage of 

 the young, which however is generally very like that of the adult; 

 they have, however, no distinctive plumage, differing from that of 

 the adult, like the majority of the Thrushes (Turdidce), this at once 

 removes them from that family. 



Tkinomials. 



" As the use of trinomials for sub-species — or better, geographi- 

 cal or local races — does not seem to be generally understood, it may 

 be explained that when a species is divided into two or more races, 

 or when two or more species are grouped as races of one species, 

 then each of these races must have a trinomial appellation. It is 

 impossible to say which is the oldest or parent form, therefore the 

 first-named race of all those grouped under one species is arbitrarily 

 taken as the typical race, and its name becomes that of the 

 species." 



" It cannot be gainsaid that the trinomial system is of the great- 

 est possible use scientifically as demonstrating the close relationship 

 of geographical forms of the same species, just as the binomial system 

 demonstrates the relationship of species of the same genus." f 



As the use of trinomials is possibly new to a great number of 

 Members of the Society, I have given the above definition from "The 

 Hand List of the British Birds", which explains their use and ad- 

 vantage very much better than I possibly could. 



Mr. Oates in the "Fauna of India " did not always take notice of 

 geographical races, some he considered distinct species, whilst others 

 he treated as local forms, only just mentioning the differences which 

 occur between them and the typical species he was describing. So 

 that, often from his descriptions it is impossible to tell whether the 

 bird he is actually describing is quite distinct from any other spe- 

 cies, or only differs in some minor detail. 



For example, in the Chestnut-headed Laughing-Thrushes ( T. 

 erythroceijlialwin, nigrimentum, chrysopterum, erythrolcema, mela- 

 nostigma, etc.), there is nothing in Mr. Oates' descriptions, which 

 tells at a glance that all these birds are really only the geographical 

 races of one species, and merely differing from each other in 

 some small detail, such as the colour of their ear-coverts, supercilium, 



* Capt. C. H. T. Whitehead informs me that the local form of Trochalepterum 

 lineatum, inhabiting the hills in the vicinity of Kohat, during the cold weather 

 descends down to the lower ranges, this can hardly be called true migration, 

 it is very i nteresting, and probably the same local movement takes place 

 amongst other species inhabiting bare and open hills. 



t"A Hand List of British Birds/' Hartert, Jourdain, Ticehurst and Witherby, 1912. 



