406 THE ZOOLOGIST. 



Rules for Mapping (Birds especially). 



(a). Red indicates the area throughout which the species is a summer 

 visitor (i. e. that over which it breeds). 



(b). Blue indicates the area over which it is a winter visitor. 



(c). Purple (i.e. blue printed over red*) indicates the area over which it 

 is a permanent resident [i.e. over which it both breeds and winters). 

 Partial inter-migration of the species within this area might be indicated by 

 lighter shades of colour, though this would be somewhat difficult. 



{d). These colours, indicating the period of residence over certain areas, 

 should be also used in conjunction with the various other indications of 

 distribution mentioned hereafter (region over which the species has become 

 extinct, or has been naturalized, its line of migration, present evident 

 changing of distribution, probable (but unrecorded) extensions of its 

 area, &c, &c), as more fully pointed out hereafter. 



(e). The lines of Migration along which the species passes to or from its 

 summer or winter resorts, as the case may be, should be represented, so far 

 as they are known, by means of arrows indicating the general route and 

 direction of migration. As, in the case of some species, a route is followed 

 in the spring migration which is different from that followed in the autumn 

 migration, red arrows would indicate the route by which a species proceeds 

 to its summer haunts, while blue arrows would indicate that by which it 

 returns to its winter resorts, f 



(/). Relative abundance of the species, or the reverse, may be indicated 

 as follows : — An unbroken patch of colouring would show the area over 

 which a species is fairly or very abundant ; the area over which a species 

 is of occasional, though more or less regular, occurrence can be shown by a 

 number of asterisks placed in regular pattern thus : — 



*t* *t' '»* *r *»' *p *£ 'i* *p *£ 'fi *h 



>\i i\i i\i >H i\i >;< :*< i]i i\i sje *. ♦ 



* i'fi * 9fc * * >;< * * >!' * * 



while isolated and altogether exceptional occurrences can be indicated by 

 isolated asterisks (thus * ), the date of each occurrence being affixed, if 

 thought desirable. In each case, of course, the colour of the asterisks or 

 other marks used would indicate whether the relative abundance over 



* Thus all the facts connected with the distribution of any species as 

 specified herein may be represented by the use of only two colours (of course, 

 excepting black), which will effect a great saving of expense in the ultimate 

 printing of the intended work for publication. 



f The "erratic movements" referred to on p. 362, though distinct from 

 true migration, might also, for convenience, be represented by arrows. 



