ME TA CA RP US—MIGRA TION 547 



middles," while in the other division, ACROMYODI, the syringeal 

 muscles are attached to their extremities. Garrod further 

 divided the Mesomyodi into Homceomeri, comprehending Tracheo- 

 PHON.« and Haploophon^, and Heteromeri. Mesomyodian 

 Families are most characteristic of the Neotropical Region, all but 

 three, Fiitidx, PhilepiUidse and Acanthidosittidae, being, so far as is 

 known, peculiar to the New World. 



METACARPUS, generally used in Ornithology for the portion 

 of the wing from the wrist (Carpus) to the root of the fingers, but 

 since the distal carpal bones coalesce with the proximal end of the 

 metacarpals, this part should strictly be called carpo-metacarpus 

 (see Hand under Skeleton). 



METATARSUS, by Ornithologists often applied to that part 

 of the foot which reaches from the ankle-joint to the root of the 

 toes and is commonly but wrongly called the Tarsus ; the distal 

 tarsal bones coalescing with the proximal end of the metatarsals 

 (see Foot under Skeleton). 



MEW, Angl.-Sax. M^w, see Gull. 



MIGRATION. Strangely confounded by many writers with 

 the subject of Geographical Distribution is that of Migration. 

 True it is that owing to the vast powers of locomotion possessed 

 by nearly all Birds, we have individuals belonging in the main 

 to certain groups, but by no means always confined to them, stray- 

 ing from their proper quarters and occurring in places far removed, 

 not only from the land of their birth, but from the country whither 

 they are ordinarily bound in their journeys, to reach which is the 

 object wherefore such journeys are undertaken. It may be that 

 in some measure this erraticism is governed by fixed laws, and 

 indeed indication is not wanting that such laws exist, though as 

 yet we know much too little to lay them down with any approach 

 to confidence. But it is obvious on reflection that granting the 

 existence of most rigorous laws of this kind — determining the 

 flight of every winged vagabond — they must be very different from 

 those which are obeyed by Birds commonly called " Migratory," 

 and year after year moving, according to a more or less fixed 

 rule, from one locality to another with the seasons as they roll. 

 The former laws would seem to be created or controlled by purely 

 external circumstances, which if they possess any periodicity at all 

 possess a periodicity of cycles, and are most likely dependent in the 

 main on cycles of the weather, but on this point observation has 

 not yet supplied us with the means of avoiding speculation. We 

 may indeed say almost without much risk of error that so many 

 individuals of a foreign species — whether North- American or Asiatic 

 — will occur in Great Britain so many times in the course of a 



