aift REPORT— 1856. 



species of conifers. And he is strengthened in this opinion by the circumstance that 

 the second American species of Cross-bill {Loxia Ampricana, Wils.) resembles on 

 the ■whole the L. curvirostra of the Old World, but differs from it, exactly in the 

 same way as the h. leucoptera differs from L. bifasciata, that is to say, by its smaller 

 size, and weaker bill with the points finer and more elongated. 



Reference was also made to a remark by Mr. Gould respecting the swallows and 

 sylvan birds in the island of Malta, whicb, " though unquestionably of the same 

 species as those of Great Britain, exhibit small local characteristics by which they 

 may be immediately distinguished, such as the length of the wings, size of the bills, 

 and tints of the plumage*." Mr. Gould was inclined to think that the shortening 

 of the wings in these Maltese individuals was connected with the circumstance of 

 their having a shorter distance to traverse in their migrations to and from Africa, 

 where they winter. 



These and several other observations, all tending to show the occasional variation 

 of the characters of birds, — more especially some by the same gentleman last alluded 

 to respecting the greater brilliancy of the plumage, according as individuals of a 

 given species were found in the interior of continents, or in insular or maritime 

 countries t, — led the author to ask, whether there is not enough on record to make us 

 at least hesitate respecting the stability, not of species in general, but of many of the 

 so-called species of Birds. When we couple the facts above referred to, with the 

 known influences of season and temperature in causing periudic changes in the 

 plumage of some species; — when we find these changes hastened or retarded 

 according as the seasons are more or less forward, prevented, it is probable, from 

 taking place at all some years> or in some localities, in which the summers are colder 

 or the winters milder than in others ; — when we further take into consideration the 

 known effect which particular kinds of food have in altering the plumage of birds in 

 captivity, the colours becoming deeper or more dull, sometimes changing to a complete 

 blackj ; — when we bear all this in mind, and recollect too how generally the offspring 

 is marked with the peculiarities of the parents, — might we not almost « p-«on be led 

 to expect, that if a species had originally extended itself ages back, or been accidentally 

 introduced into other countries than that in which it had been first created, these 

 countries having a different climate, or the bird finding there a particular food, cal- 

 culated to exercise a permaimtt influence of a like kind to that which is only seasonal 

 ov occasional elsewhere, — it would become, in the course of generations, stamped by 

 some permanent variation of plumage, just as we have the different races of men, 

 each bearing so remarkably its own distinctive characters, yet surely all of one species, 

 as the best ethnographers and physiologists of the day seem disposed to admit ? 



An opinion was expressed, that where two species are really distinct, there will 

 generally be some difference of song, nidification, or other habits, accompanying any 

 slight differences of plumage, as in the instance of Sylvia trochibis and -S. rvfa, which 

 no one would mistake when heard in the woods, though difficult to distinguish in 

 hand. And though we must for a long time be necessarily ignorant of the habits 

 of a large number of foreign birds, the author thought it far better, in the case of any 

 supposed new species, especially where only one or two specimens have been obtained, 

 to abstain from naming it for the present, unless characterized by well-marked and 

 unmistakeable peculiarities of form or plumage, rather than incur the risk of increasing 

 the synonyms of some previously known species, from which it may not prove to be 

 distinct. Until further information respecting it were obtained, it would be prefer- 

 able to regard it as a mere local race, to which race, however, there would be no 

 objection to append the name of the particular country or district in which it was 

 found. 



Before concludmg. the author made some remarks on the variation of shells, 

 noticing chiefly some valuable communications to science by Dr. Gray§ and Mr. 

 M'Andrew||, who have shown that the characters of many species of shells greatly 

 alter, according to the depth of sea they inhabit, or the more or less exposed situations 

 in which they are found. He then expressed a hope that these variations, along with 



* Mentioned by Mr. Wollaston in liis work 'On the Variation of Species.' 



t Ann. and Mag. of Nat. Hist. vol. x\ii. p. 510. 



J S2e Bennett's edition of White's Selborne,' p. 165, note. 



§ Phil. Trans. 1833. || Edinb. New Phil. Journ. vol. xlvi. p. 355, &c. 



