1914] Kershaw—The Alimentary Canal of a Cercopid 65 
mdey, middle discocellular vein (in this case, and usually, a portion of media- 
one). 
Idev, lower discocellular vein (the portion so marked is a portion of the stem of 
media one-plus-two, but as ordinarily defined the short cross-vein m. would also 
be considered part of it). 
Ist A is a concave vein, and when it becomes rudimentary is known as the sub- 
median fold. 
The veins, hum., Sc’, se-r, r, cu-Ist a, Ist-2d a, and 4th a, are lost in almost all 
higher forms. 
i, Intercalated cell (reckoned as part of the discal cell). 
ace. ce, Accessory cell (reckoned as part of the discal cell in micros- and butter- 
flies, where it is more or less completely fused with it, but not in most moths, where 
it is perfectly separated, when present). 
Fig. 2. Portion of bleached wing-membrane, showing points of attachment of 
scales and aculee. 
THE ALIMENTARY CANAL OF A CERCOPID. 
By J. C. Kersuaw. 
The following brief notes refer to Tomaspis saccharina Dist., a 
pest of sugar cane in Trinidad, West Indies, where the nymphs 
feed on cane roots and the adults on the leaves. In the nymph of 
this Cercopid the air, which all sucking insects doubtless imbibe 
in quantity along with the liquid food, appears to pass through 
the alimentary canal and be utilized in forming the air-bubbles 
coated with mucinoid which are emitted from the anus and form 
the froth in which the nymph lives. After examining this Cer- 
copid I am the more inclined to believe that (as stated in a pre- 
vious. paper on Flata in Psycue) the “‘food-reservoir”’ in the head 
of Flata functions in part as an air-separator to rid the liquid food 
of superabundant air before it passes through the alimentary canal. 
In the Cercopid nymph, however, the air is directly utilized, as 
mentioned above. In this Cercopid and in Cicada the diverticu- 
lum or pouch of the midgut (forming the “food-reservoir”’ of the 
head in Flata and the filter-chamber of the thorax in Cercopid* 
and Cicada) is almost filled up by the zigzag course through it of 
the posterior part of the midgut and the anterior part of the mal- 
pighian tubes. This diverticulum, pouch or filter-chamber is 
entirely situated in the thorax, as are also the diverticula of Per- 
kinsiella and other Homoptera mentioned in the paper referred to 
above; only entering the head in Flata, Pyrops and Dictyophoro- 
