32 
ROYAL HORTICULTURAL SOCIETY. 
laria), and also in those flies wliicli do not cat pollen but live ex- 
clusively upon juices, for instance Bomhjlius, the two valves of the 
proboscis serve no other purpose than to protect and guide the 
sucking tubes ; but in the flies which devour pollen, besides this 
function, there is also that of grinding the pollen, for which they 
have special adaptations, for the margins of the two valves at the 
point of union arc transversely dentate with flne parallel bands of 
chitine. Probably the greater or less distance of these bands in 
difl'erent s])ecies is related to the difl'ereut size of the pollen upon 
which they feed." 
[Additional note, March 10. 1873.] 
The subject has also recently been investigated by the well- 
known naturalist, Mr. Edward JS'ewman, whose conclusions on this 
point are equally at variance with those of the majority of his 
brother-entomologists. He asserts unhesitatingly (" Entomologist " 
for Jan., 1873, p. 291, and for March, p. 336) that the ordinary 
food of Eristalis^ as well as of many other Diptera, is pollen ; 
/'Masses of this and other solid substances being found in their 
stomachs undissolved and unaltered after passing through the entire 
length of the leathery and extensile promuscis." Whether, how- 
ever, the pollen-grains are entirely unaltered, or whether their 
liquid contents or fovilla" is extracted for the nourishment of the 
insect, is a point which cannot at present be considered as decided, 
and which must form the subject of a future series of observations. 
In a recent communication to the " Eield," Mr. Newman thus 
describes the process, as observed by him, by which the Syrphidce 
detach and devour the pollen of plants, which it is interesting to 
compare with the independent observations of Prof. Miiller : — 
Uristalis tenax, pertinax, and sequax are all greedy devourers 
of ])ollen, and all of them devour it in the same manner. They 
thrust their proboscis among the florets, separate the two spreading 
valves with which its extremity is furnished, grasp a cluster of 
pollen-granules, detach them from the flower, and swallow them. 
The operation of detaching the pollen-granules is not performed 
without some skill and exercise of ingenuity, for in many flowers 
the granules are united together by slender tenacious threads, 
which must be broken before the granules can be swallowed. This 
swallowing of the pollen is very obvious to the patient observer ; 
the granules, a few at a time, ascend the leathery proboscis and 
thence descend into the stomach, which becomes gorged with them, 
and from which they may be extracted, after the insect is killed, in 
