NATURAL HISTORY MISCELLANY. 313 
branes acting as parachutes. The drying of the flying membrane 
in the air would prevent the small but numerous motions neces- 
sary for true flight, and the animal, therefore, suddenly drops when 
the membrane becomes stiff. He could not see how the drying of 
the pectorals would effect their action as parachutes. 
At the same time there were seen small Portuguese men-of-war 
(Physalia) no larger than an olive, and without the purple reflec- 
tions of the larger ones so often met in the Atlantic. Whether 
these were the young, or full-grown individuals, he did not know. 
He saw none larger than these, and they were not numerous. 
As he approached the coast off the Gulf of California the pe- 
trels disappeared and were replaced in an hour or two by white 
gulls, about the size of Bonaparte’s gull, but either entirely white 
or with a very slight lavender-blue tinge on the back and wings. 
These had an entirely different way of alighting and rising from 
the water; they did not push forward their feet to arrest their 
course, but circled round like pigeons until their headway was 
stopped, then quietly settled upon the water immediately folding 
their wings. They also rose directly from the surface without 
running along as the larger winged petrels did. 
Mierations oF Morus.—Our readers are familiar with migra- 
tions of butterflies, and now we see noticed in ‘‘ Nature” the mi- 
gration in “amazing numbers” of Urania Leilus, which mimic 
butterflies not only in their size, and disposition and colors of their 
scales, but also in this habit of swarming, which we do not remem- 
ber to have seen noticed in other moths. This Urania was seen 
flying in swarms across the Isthmus of Panama, and also by anoth- 
er person near- Para, Pernambuco, and Rio Janeiro. ‘From an 
early hour in the morning until nearly dark these insects passed 
along the shore in amazing numbers, but most numerously in the 
evening. It was very seldom that one was seen in the opposite 
direction.” 
The Urania is sects, as “ Nature” suggests, “something be- 
tween a skipper [Hesperia] and a hawk moth,” but a true Geome- 
ter. A careful examination of the structure of the moth shows 
us that it is nearly allied to Cherodes and Urapteryx. To this 
position Guenée has also assigned it. 
RAPID GROWTH or THE Pickerex (Esox reticulatus). — This fish, 
x ey bad characters, makes a worse show the more he is studied. 
. L. Sturtevant investigated their powers of eating, in the 
