M323" 
Netore (012s (prs 
* Wf (URE [Frsruary 15, 1930 
Pp’ The Blowfly’s Mouth. 
\ 
THE proboscis of the blowfly has been so often 
1 figured and described that students generally have no 
difficulty in understanding its structure and mode of 
working. There is, however, one small ambiguity that 
beginners are liable to find somewhat perplexing, 
especially when only balsam preparations are used, 
namely, the use of the word mouth to describe the 
- Opening in the centre of the terminal dise. That this 
opening is not the mouth in the sense of being the f 
entrance to the pharynx is apparent when one dissects | 
a well-distended proboscis that has been cleared in i 
potash. If the dise is snipped off and examined under | 
| 
water without pressure (see Fig. 1), the opening is 
= 
Photo. (J. Manby. 
Fie. 1.—Dise of blowfly’s proboscis. 
8 th Se 
found to be identical with the gap lying between the 
two lobes (labella), particularly with the small central 
region, which is nearly but not quite partitioned off 
from the upper part and which is continuous behind 
with the channel-like groove in the haustellum. 
If the name mouth is retained for this region of the 
disc, the question arises what the aperture at the other 
end of the haustellar groove should be called. Unlike 
the gap in the disc, this small and deeply placed aper- 
ture is concealed from view and somewhat trouble- : 
some to find unless the overlying parts be first removed. f 
When this is done—when, for example, the haustellum 
is cut away—the aperture is seen lying between the 
epi- and hypopharynx at the end of the rostrum ; and 
since, besides being associated in this manner with 
appendages that are plainly oral in character, it opens 
directly into the front portion (‘‘ buccal cavity ”’, 
Patton and Cragg) of the pharynx there seems to be 
good reason why it, rather than the opening in the 
q dise, should be called the mouth. 
T. H. Taytor. i 
The University, 
Leeds. 
