AVES. 
99 
vidual variability in the species, which renders the task of describing them 
difficult; but from this wealth of material the authors have greater con- 
fidence in the opinions they declare. Two almost entire skeletons (supposed 
to be male and female) have been mounted ; and these are described in much 
detail, Prof. Owen’s paper on Didiis (Zool. Rec. iii. pp. 104, 105) being fol- 
lowed as a pattern, and the whole compared bone by bone with that bird and 
also with JDuhmctdus. From the latter PczojyJiaps differs quite as much as 
does JDidus, to which it is nearly allied. The most remarkable feature is the 
presence of a bony knob on the radial side of the metacarpal bone, which is 
very largely developed in the supposed males, and only slightly in the sup- 
posed females. This most singular and unexpected discovery corroborates 
the veracity of Leguat, who described the males as having a little round mass 
like a musket-ball under the wing. A microscopic description of its struc- 
ture, by Mr. J. Gedge, is added. The differences between Didus and Pc 2 o- 
phaps are then pointed out, and more detailed generic characters assigned to 
each. After reference to the narratives of the old voyagers, it is suggested 
that both birds were most likely exterminated by feral swine. The extra- 
ordinary fidelity of Leguat’s account is next considered. It is certainly 
borne out by the facts in every case, save perhaps one, the inference that the 
bird was monogamous, reasons being given for doubting this particular. 
After this the authors indulge in some speculations as to the origin of species 
and the process of Natural Selection, with remarks on the ornis of the Mas- 
carene Islands. Whether this has resulted from that process must remain an 
open question ; but they conclude by declaring their belief that Pezophaps 
and Didiis must have sprung from the same parent stock. [ Cf. Ibis, 18G8, 
p. 362.] 
GALLINiE. 
HuxiiEY, T. H. On the Classification and Distribution of the Alectm'o- 
moipluB and Heteromoiphce. Proc. Zool. Soc. 1868, pp. 294-319, with 
Map. 
The generalizations to which this paper leads have been already recounted 
[see “General Subject”]. Its first section is a consideration of the 
proper limits of the Alcctoromorphce and of its subdivisions. The name is 
now restricted to the Phasianid(p. [including the I'ctraonidcc], Met/apodiidcCj 
and Cracida^, leaving out the Tumkidcp. and Ptcroclidcc [of which more pre- 
sently]. The osteological character of these three groups is given ; and it is 
then shown that they are divisible into two sections, which the author terms : — 
PeristcropodeSj composed of the Megapodiidm and Cracidee ; and the Alectoro- 
podes, formed by the Galline, Pavonine, Phasianine, and Tetraonine birds — in 
other words, the Phasianidoi and Tetraonidai of most authors, which present 
two types of structure,” one of which may be termed Galline and the other 
Tetraonine. These two series of forms meet among the I’artridges and 
Quails — Perdix lying on the latter and Caccabis, Rolhdus, Francolinus^ and 
Coturnix on the former side of the boundary. Odontophorus probably goes 
with Perdix. The diflerent facts on which this opinion is founded are ad- 
duced in considerable detail. Then comes a section on the relations of the 
Pteroclidce and JIemip>odiidce \ Turnicid(P\ to the irno Alectoromorphce, and the 
first are shown to be completely intermediate between the last and the Pens- 
teromorphee. As they cannot be included in either group without destroving 
• H 2 
