IlfTEODUCTIOIf. 



XXXlll 



In the Tingididfe the distinction between corium and membrane 

 is less distinct, and these terms are scarcely used in the descriptive 

 terminology, the membrane being reticulated and resembling the 

 other portion of the hemelytra. 



The legs do not call for much comment. They are variable in 

 structure, but are fully described in the diagnoses of genera and 

 families. Thus the' coxse may be placed close together or con- 

 siderably apart, as in some Coreidae ; the femur may be slender or 

 thickened and spined ; the tibiae may be simple, serrate or pilose ; 

 the tarsus may consist of two or three joints and may bear a claw 

 or claws ; the structure is also of an adaptable character in the 

 aquatic species. 



The number of abdominal segments is a question of considerable 

 difficulty, and they have been variously estimated as being nine, 

 ten, or eleven in number. This is due to the method of anatomical 

 study and the inclusion or non-inclusion of the anal appendages as 

 segments or otherwise. If, however, the apparent number be 

 accepted, as is generally done in classification, 

 there are six segments, the basal often much 

 concealed, apart from the anal plate and 

 organs. The last named are often, as in 

 Lepidoptera, used as specific characters, and in 

 fresh or spirit-preserved specimens are doubt- 

 less of the greatest validity ; but when, as 

 is more often the case, they have only been 

 observed in dried specimens, in which they 

 are naturally more or less distorted, an ele- 

 ment of uncertainty is introduced. For 

 certitude a dissection requires to be made, 

 and in the present position of Ehynchotal 

 stud}^ this can scarcely be always expected. 



The females of many Heteroptera and 

 Homoptera possess a well-developed ovi- 

 positor which serves to lacerate the leaves 

 of plants and to introduce the eggs into the 

 orifice thus made. 



Stridulatory organs have been discovered 

 in the Corixidse and doubtless exist in many 

 genera of other families. Stridulation may 

 be almost universal in the Insecta, althougla 

 it is not detected by our imperfect sense- 

 organs ; the investigation of this subject is 

 certain to be more pursued in the future, 

 aided by delicate testing-apparatus. 



. Fig. 7. 

 Leg of a Peutatomid. 



a. Coxa. 



b. Trochanter. 



c. Femur. 



d. Tibia. 



e. Tarsus. 



1, 2, 3. Tarsal joints. 



Internal Anatomy. — To adequately describe the internal anatomy 

 of any insect requires ample space and a wealth of illustration ; in 

 fact it is a subject by itself. The student may be referred on this 

 investigation to Packard's 'Text-book of Entomology' (1898), 



VOL. I. "c 



