778 The American Naturalist. [September, 
member of the family Fringullide in its extreme thickness ; in 
others (members of the so-called genus Cactornis) slender and 
decurved ; in others very acute, with straight outlines, and, in 
others still, elevated and arched at the base. The most ex- 
treme forms are, however, so gradually connected by interme- 
diate types, that there seems no possibility of satisfactorily sub- 
dividing the genus into two or more sections. The extreme 
modifications of the bill and some of the connecting forms are 
shown in the outline illustrations on plate LVII. 
“The reduction of Cactornis to a synonym of Geospiza has 
already been made in my paper describing the new species of 
Galapagos birds in Dr. Baur’s collection, in which is announced 
the discovery of species which absolutely bridge the previously 
existing gap between the so-called genera Geospiza and Cac- 
tornis, thus necessitating the suppression of one of those names 
(the latter, according to the rule of priority). Dr. Baur, who 
has had the advantage of studying these birds in life, disap- 
proves of this, as the following extract from one of his letters 
will show: ‘I should like to make a few remarks, if you will 
permit me, about Cactornis and Geospiza. You place the spe- 
cies of these two genera in one genus, Geospiza. I do not 
think that this is natural. Both have their peculiar represen- 
tatives on the different islands, and if you place them together, 
this peculiar differentiation of each is lost sight of. Cactornis 
is more slender than Geospiza, and has many more black in- 
dividuals. I would keep the two genera apart, and would not 
hesitate to place Geospiza propinqua in Cactornis.’ I am quite 
willing to adopt Dr. Baur’s views concerning the position of 
G. propinqua, which I had compared with G. conirostris (a true 
Geospiza); but, while admitting that it would be very conven- 
ient to recognize Cactornis if any definite characters could be 
found which will serve to separate them. The character which 
comes nearest to doing so, apparently, the relative width of the 
mandibte between the bases of the rami to the length of the 
gonys, which is very much less in typical Cactornis than in 
true Geospiza. This greater compression of the bill even serves 
to trenchantly separate Cactornis propinqua from G. conirostris, 
some individuals of which are almost precisely alike in the 
lateral profile and measurements of the bill.” 
