( 154 ) 



the old genns Camarhynchns totally black iudiviiluiils are not luiiiid, liuf it seems 

 that all the Geospizae and <'acfor»/t/irs in the old sense, except " Cuctonu's " 

 paUidiis, have the adult nwle black, with the exceirtion of the nnder tail-coverts, 

 wliich have white borders. The bill is only black in black-plumaged adult 7nales ; 

 but not in all. It seems evident that those with brown bills are less aged than 

 those with black bills ; but why the hitter, and in faet black individuals of most of 

 the species, are so rare is quite unexplainable to ns. 



The variations in size are great within some of the species, and j'ounger birds 

 have very small bills— a fact which has more than ouce led authors to mistakes. 



1. Geospiza mag'iiirostris J. (iould. 



Geospha magnimslrh, J. Gould in P. Zool. Soc. Lotiil. 1837. p. 5 ; Zool. Beagle, III. Birds, p. 100, 

 PI. XXXVI. (1841) ; Salvin in Trann. Zool. Soc. Loml. IX. p. 478 (187G) (bill) ; Shar'pe, Cat 

 B. Brit. .l/«s. XII. pp. 6, 7 (fig.) ; Eidgway I.e. p. 512. 



It is very strange that this largest-billed form of (inches from the whole group 

 has not been met with by any collector since Darwin's visit to the CJalapagos. 

 There are, in our opinion, only two possibilities : 



(1) That this form is a larger representative of G. strenua on Charles Island. 



(2) That the few specimens in the British Museum are exceptionally large 

 individuals of G. streiiwi. 



The first theory is probably the correct one. The origin of the type-specimens 

 is not exactly known. Probably neither Dr. Sharpe nor Mr. Ridgway remembered 

 in the moment when they treated of these finches what Darwin said in his .hurnal 

 of Jiesenrr//e.s (new edition, 1890, p. 420) about his omission to label his collections. 

 He there says : " Unfortunately most of the specimens of the finch-tribe were 

 mingled together, but I have strong reasons to suspect that some of the species of 

 the snb-group Geospiza are confined to separate islands"; and again, on p. 421, 

 '•whereas the numerous specimens shot either on Charles or on Chatham Island 

 (for the two sets were mingled together) all belonged to the two other species." 

 It is thus evident that the locality of Chatham Island for G. magnirostria is open 

 to doubt. We have no donbt that all the specimens came from Charles Island. 

 Neither Dr. Habel, nor Baur & Adams, nor the recent collectors whose collections 

 are before us, found any very large Geospiza on Charles Island, not even G. strenua. 

 The " Albatross " only procured one specimen, which Ridgway refers to G. strenua. 

 Considering, however, that it is an immature bird, and that the two forms G. 

 magnirostri.-i and strenua are so closely allied that they dilfer only in having the 

 wings and bills a few millimetres larger or smaller, it is quite possible that it is 

 a young of G. magnirostris. It is probable that G. magnirostria is exterminated 

 or extremely scarce. This is qnite possible when we consider that Xeaomimus 

 trifasciatus has disappeared from Charles Island, and that these finches, according 

 to Darwin {Zool. Beagle, t.c. p. 100), did " much injury by digging up roots and 

 seeds from a depth of even six inches." It is therefore to bo supposed that they 

 were killed by the colonists, who complained of their injuries, and who first settled 

 on Charles Island about 1830. The locality Chatham Island is certainly wrong, for 

 no big-billed form has ever been found there ; and there are no early settlers who 

 might have killed them long ago. 



The dimensions of the three black specimens in the British Museum are : 

 cnlmen, 26-5, 27, 27 mm.; height of bill at base, 23-5-24 mm.; wing, 91, 91, 

 '■••'3 mm.: tarsus, 25 mm. 



