OF SUCTION IN LYGUS PABULINUS. 703 
them is connected with the maxilla of its side by an interlocking 
arrangement. 
(ii.) The tips, which are pointed, are ornamented with recurved 
hooks, the number and size of which seem to vary in different 
species. The number varies from 7 to 9 in L. pabulinus. They 
are bigger towards the tips of the mandibles but get reduced 
posteriorly. The hooks will tear the tissues when withdrawn 
from them with the maxillary stylets, though this arrangement 
will not prevent their entrance into tissues. Their function will 
be clear later on (text-fig. 23, T.Md.). 
(II.) Anatomy. 
The stylets are chitinous, the chitin being lined by the chitino- 
genous epithelium which forms a continuous layer under it. 
Kach of the stylets is enclosed in a sheath which is continuous 
with the integument of the head. This shows that both stylets 
have been invaginated in the course of their development, as is 
demonstrated by Heymons (text-figs. 4-7, Mx.Sh., Md.). 
The retort-shaped organs. (Text-figs. 5, 6, 20, 21, Poc.Or.).— 
These are characteristic of the Rhynchota (Heteroptera and 
Homoptera). Mecznikow (49) has described them as the structures 
Text-figure 11. 
, Lygus pabulinus. 
Transverse section, showing thickening of the floor of the pharyngeal duct 
(cf. figs. 10 A and 12). 
For explanation of the lettering see p. 693. 
from which the new maxille and the mandibles are formed, but, 
as is shown above, they are not new structures at all. They are 
nothing, in fact, but the swollen bases of the stylets, the swelling 
being formed during development. They are the same as the 
Taschen-formigen structures of Heymons. 
They are oval and curved laterally outward. They are found 
