Hagen.] 40 8 [January , 
of galls on leaves, upon the age and vigor of the leaf. Probably the 
difficulty will be corrected by better phraseology. The first class con- 
tains the galls of Hemiptera and Acari besides the galls of other ani- 
mals than Arthropoda, and plants. The second class contains all 
galls of Diptera, Lepidoptera, Coleoptera and Hymenoptera. 
The farther division into external galls and internal galls is not a 
new one, but agrees well with the facts. To the first belong all 
Hemiptera and most of the Acari, to the second some Acari and An- 
gaillula. 
The divisions of the second class are called “ Mantelgallen ” and 
“ oeschlossene Gallen” by Mr. Beyerink. I have adopted, according 
to Dr. Thomas’ views, the expressions used in the first class. 
The division of Larva galls and Imago galls by Mr. Beyerink is 
apparently correct, though some of the galls are not put by him in 
the right place. The external galls of the larva class all belong to 
Cecidomyia; the internal galls, subdivided by Mr. Beyerink into two 
groups and several sub-groups, contain some Diptera and all Lep- 
idoptera and Coleoptera. The imago galls contain all Hymenoptera. 
Here again objection is made by Dr. Thomas to the expressions used 
for the Cynipidae. Indeed these galls are often not full grown, be- 
fore the larva is hatched from the egg. 
Mr. Beyerink gives with every group and sub-group the number 
of species of galls known to him. ‘There are mentioned for Hemip- 
tera 66; Acarus about 111; for Diptera 177, three-fourths of them 
Cecidomyia; for Lepidoptera 14; for Coleoptera 36; for Hymeno- 
ptera 130, 16 of them Tenthredo. 
I should state that most of these figures include only the European 
species, except in the case of the Cynipidae. 
For those students not yet acquainted with the rational nomen- 
clature proposed six years ago by Dr. F. Thomas, I add his principal 
names. The term Cecidium includes every deviation in the develop- 
ment of plants, and, therefore, comprehends not only the true galls, 
but also the false galls and the hypertrophies to the phyllomania. 
Cecidium is divided into Acrocecidium, the bud-galls and all related 
to them; and Pleurocecidium, all the rest. Dr. F. Thomas remarks 
that in Mr. Beyerink’s classification the simple galls belong mostly 
to Pleurocecidia, the compound galls to Acrocecidia. All animals 
producing galls, are named Cecidozoa; all plants producing galls, 
Cecidophyta. It is obvious that such a uniform nomenclature has a 
decided advantage over the older one. 
