go2 General Notes. : [ November, 
these organs are metamorphosed branches, although some doubt: 
may arise as to whether the distal ends are true corbule or not. 
If we compare Hippurella with Callicarpa Fewkes, all question 
as to the latter point is silenced, for in Callicarpa we have a struc- 
ture which is undoubtedly a true corbula similar to that of Hip- 
purella. 
In Callicarpa we have a hydroid with simple stem, bearing 
pinne arranged regularly and alternately along its whole extent. 
On the main stem from which these pinne spring, there also arise 
corbule which closely resemble in shape spikes of wheat or bar- 
ley. At that point on the main stem from which these arise there 
is no variation in the normal arrangement of the pinne, and no 
omission of a single pinna such as would be expected if the spikes 
were modified pinne. The corbule arise like any branch, and in 
their arrangement on the stem, no less than in their shape, bear 
every resemblance to metamorphosed branches. 
The genus Callicarpa has still another interesting resemblance 
to Hippurella bearing on this homology. While the latter genus 
has the distal extremity of the branch modified into a corbula, 
and the proximal end remains normal with true pinnae, Callicarpa— 
has the whole branch changed in the same way, and it Is desti- 
tute of those proximally placed pinna which characterize the 
corbula of Hippurella. 
In conclusion, considering the corbula of the three generé, 
Pleurocarpa, Callicarpa and Hippurella, we are led to give to it 
a different homology from that which has been suggested for the 
same structure, as I believe, in some species of Agalophema. 
The strongest evidence in support of my theory is foun Ss 
Pleurocarpa, where the corbula is undoubtedly a modified branc™® 
Are we to suppose that the corbula is not homologous 1n differ- 
ent genera, or that in one genus it is a modified pinna, while 1 
another a metamorphosed branch ?—¥. Walter Fewkes, Cam- 
bridge, September, 1881. 
Micration oF Birps ar Nicut.—The vexed questions oa 
garding the migrations of birds and whether they fly by night ate 
at great elevations have been elucidated by Mr. W. E. D. eh 
the Bulletin of the Nuttall Ornithological Club for April. While, 
. with some friends, looking through the 9% inch equatoria’ @ 
birds, among which were plainly recognized warblers, apnea 2 
woodpeckers, and blackbirds, the relative numbers being i 
order of kinds given. Among the finches Mr. Scott ident 
Chrysomitris tristis, and the blackbird was the Quiscalus purpureus 
With tare execeptions, the birds were seen to be flying” ‘ 
oo rth-west to south-east. By observing the height of the mo os 
1) - 
og foes 
