PHILIPP C. ZELLER AS A BIPTEROLOGIST 
139 
life, and of facts about geographical distribution derived from a 
large personal experience in different parts of Europe. The de¬ 
scriptive part of the work is treated with rare detail and accuracy; 
notices on the varieties of the species are sometimes almost too 
redundant (for instance, in the Tabanidae). Among the compara¬ 
tively small number of genera and species that are treated of, 
many new characters and subdivisions are introduced, often with 
singular perspicacity. But the most attractive and novel depart¬ 
ment of the work is biological, consisting of accounts of the 
habits and of the demeanor of flies. To illustrate Zeller's man¬ 
ner, I shall reproduce a few instances. About Bombylius he 
says, p. 14 : — 
“ The mode of flight of the true Bombyliidae is not unlike that of Syrphns. 
They hover for some time in the same place, jerk off suddenly, and then 
gradually sink, and thus approach the flowers they intend to suck. In the 
meantime they hold their hind legs horizontally, diverging; the front and 
middle pair almost hanging, and kept close together; the latter are often 
rubbed against each other, just as house-flies rub their front legs when 
cleaning themselves with them. The proboscis is horizontally stretched 
out. When near a flower, they generally touch it with the tips of their 
front legs, without, however, resting upon it; the wings vibrate without 
interruption, and support the body evidently more than the legs. The pro¬ 
boscis is inserted in the flower, whenever it is possible, vertically. For the 
night’s rest they alight upon blades of grass or on flowers. When an enemy 
is approaching, they vibrate their wings, without being able to fly. Later 
in the evening, when the air is cooler, they become incapable even of this 
sign of life. The sound emitted by them during flight is, in some species, 
very loud, and resembles the piping of Culex, except that it is louder. The 
sound of Bombylius minimus is very low, and yet audible, when the ear is 
brought near it.” 
Not content with such generalities, Zeller notices the peculiari¬ 
ties of behavior of almost every species: Bombylius minimus : “ Flies 
near Berlin, Frankfort (on the Oder), and Glogau in pine forests, 
about open, sandy places in July. Ilis favorite flower is Thymus 
serpillum. He ofteu alights on the sand. I have already spoken 
of his low piping tune.” Similar details about Bombylius minor , 
posticus, concolor, etc., eight species in all. 
Concerning Anthrax, he says (p. 25) : — 
