468 NATURAL HISTORY OF BIRDS. 



croesing continually prevents ; but if continental India were broken up into three or 

 four large islands (a change which the southern extremity of Asia has already under- 

 gone), we can liardly doubt but that a form specially adapted to the conditions, 

 physical and orgariic, of each island would be develojied by natural agencies from the 

 variable material that we know already exists there. This segregation has already 

 taken place to a remarkable extent in the archi(>clago. Generally speaking, each 

 island, or little grouji of islands, lias its peculiar species distinct from those of the 

 islands that surround it. Some of these cases of localized species are among the most 

 extraordinary known. The little island of Banda, hardly more than a mile across, has 

 a species j)cculiar to it. Ternate, a mere volcanic satellite of Gilolo (Ilalmahera), and 

 not more than ten miles frotri it, has a Pitta all to itself, though closely allied to the 

 distinct species which inhabits the large islands of Gilolo and Batchian. The small, 

 rugged metalliferous island of Banca, between Sumatra and Borneo (but so close to 

 the former island as to seem only a detached frngment of it), has actually two species 

 peculiar to itself ; while, what is still more strange, the two allied species of which 

 they seem to be modifications {P. cyanojHera and P. mtidleri) are both common to 

 the great islands of Sum.it r;v and Borneo." 



This hitter case Dr. Wallace then explains by showing that Banca was already 

 isolated at a time when Sumatra and Borneo were connected with the Mahiy penin- 

 sula, and that the nearness of Banca .and Sumatra is quite recent, the nearest coast of 

 the latter consisting of a soft alluvial soil, newly-formed by the action of tropical 

 rains on the mountains w.ay back in the interior. 



The motions of the pittas he describes as very pleasing. They never seem to hurry, 

 and yet get .along at a great rate by hopping, generally on the ground, but occasion- 

 ally perching on a stumj) or bush, .and, when hard pushed, taking a long, straight, 

 and silent flight. The voice of the smaller species he met with was a j)laintive whis- 

 tle of two notes, the second lengthened out and quickly succeeding the first, while 

 the larger species seem to have three notes. The ])ittas seem not to answer to their 

 vernacular name, 'Old World ant-thrushes,' as, according to Wallace, these insects 

 are not their favorite food, which chiefly consists of coleopters, small orthopters, and 

 worms, after which they dig with their jiowerful bills. 



The remaining forms of the jireseiit sujter-family, without a single exception, in- 

 habit the New World exclusively. Garrod discovered a peculiarity in the structure 

 of some of them already mentioned, viz., that the pipras and cotingas have the femoral 

 artery developed, in a word, are hetcromerous, wiiile llie cock-of-the-roek and the 

 tyrant-birds agree with .ill other birds in having the sciatic artery performing the duty 

 as chief artery of the thigh, or are homa'omerous. We are .absolutely ignorant, how- 

 ever, of the taxonomic v.aluc of this character, and we are inclined to think that it is 

 of no more account from a systematic jioiiit of view than is in most cases the diversi- 

 ties in the arrangement of the carotids. As, moreover, only few species have been 

 investigated as to the vessels of the thigh, we shall disregard this character altogether 

 in our present attempt. 



The family Tyk.\xnid.s:, as a whole, may well be termed tyrant-birds, for a pugna- 

 cious temper and a tyrannical irritability towards other members of the feathered 

 tribes, es])ecially the raj)acious birds, seems to pervade the whole grou]i. Such a term 

 is the more expedient, since in this polytypical family of more than three hundred and 

 fifty species, it is difficult to invent suitable English appellations for the different kinds, 

 and we may now style various birds tyrant-chats, tyrant-wrens, tyrant-flycatchers, etc., 



