Xxill-xxiv| Gets") 
Scudder and others have recorded as being migratory in the 
eastern States, moving in large flocks north and south with 
the varying seasons. 
“The other case to which I refer is the gathering or ‘ semb- 
ling’ of many thousands of the convergent lady-bird, Hippodamia 
convergens, on the ground under the fallen leaves in the decidu- 
ous forest of the low mountains near this University. We have 
taken as many as 40,000 of these beetles in a circular space of 
not more than ten feetradius. These beetles, when active, are 
found normally in the great orchards of the Santa Clara Valley, 
which lie at the foot of these mountains, feeding in the 
orchards on the scale insects and plant lice which are abundant 
there. But in winter the lady-birds leave the orchards, move 
up the mountain-side and hibernate as I have described. In 
fact, we are not acquainted with the full life history of this 
insect, not knowing how many generations appear in the year, 
or whether the mating is accomplished in the fall before 
hibernation, or in the spring after hibernation, so one cannot 
be sure that the case substantiates your suggested theory of 
gregarious hibernation as a means for quick mating in the 
spring. 
‘‘A third familiar example of ‘sembling’ to be noted in 
California is the gathering in great numbers of the butterfly, 
Pyrameis cardui, repeatedly observed in Southern California 
near Claremont village.” 
The PresIpDENT then read a short paper bearing on the same 
subject, entitled “A possible explanation of insect swarms 
on mountain-tops.” The speaker said that he had been led 
to make this communication in consequence of Mr. G. C. 
Champion’s exhibit at the last meeting of Dorcadion from 
Spanish mountain-tops. These specimens and the description 
of Coccinellidxe on the summits revived the speaker’s memories 
of his visit to the Sierra Guadarrama in July 1902, and of the 
hypothesis which had suggested itself as an explanation of the 
similar and kindred phenomena which had come under his 
observation. On an isolated mass of rock near the summit of 
Penalara (about 7700 feet), behind La Granja (San Ildefonso), 
he had found, on July 25, 1902, Coccinella 7-punctata under 
every stone, Dorcadion hispanicum crawling about every- 
