4.90 MODERN CLASSIFICATION OF INSECTS. 
mouth of the suctorial Hemiptera, is probably employed in puncturing 
the flesh. At rest, these organs are defended by the labial palpi 
(jig. 123. 3, 4. Ll. p., and 6.), which unitedly form a tubular haus- 
tellum, and which Duges figures as 5-jointed (Ann. Sc. Nat. tom. xxvil. 
pl. 4. f. 9.), and Curtis describes as 4-jointed, although he represents 
them in Pulex* as only 3-jointed, which appears to me to be their 
true structure, having an internal membranous connection. Latreille 
also describes them as 3-jointed (Gen. Cr. tom. iv. p. 365.). These 
palpi arise from the apex of a small membranous labium (jig. 123. 
6. 0, and jig. 123. 3. 0), which is inserted upon a still smaller mentum 
(fig. 123. 6x); the maxille (lamine KK. and S., biters Hook, 
Jig. 123. 3, 4. mx.) are small, lamelliform, coriaceous, and subtri- 
angular appendages, at the sides of the mouth, which appear ar- 
ticulated+ near the tip; and the maxillary palpi (antenne A. & S., 
feelers or smellers Hook, fig. 123. 3, 4. m. p.) arise from their base at 
the anterior emarginate extremity of the head, and are porrected or 
rest upon the rostrulum, being composed of four joints; from their size 
and position they have been by many authors mistaken for antennz 
(“antenne, potius palpi,” Latr. Gen. vol. iv. p. 363.). 
The eyes are placed at the sides of the head, and are small and 
round {, behind each of which is a small aperture, described as ordi- 
narily closed by a moveable valve within which the antenne are placed ; 
these are minute articulated organs, varying in form in the different 
species, composed apparently of four joints (jig. 123.9. ant. of P. 
Canis, 10. ditto according to Duges), the third of which is very minute, 
and forms the cup-shaped base of the terminal joint, which in some 
species is furnished with numerous transverse incisions, which have 
been considered as so many distinct articulations by Curtis (antennz 
of Cer. elongatus 8-jointed ; antennze of C. Talpae 10-jointed, Curtis, 
417. and 417. a); occasionally these organs are withdrawn out of their 
cavity, and carried erect§ as in P. Musculi Duges (fig. 123. 8. a, 
ax being the valve beneath which they lie in repose). 
* He figures them as 4-jointed in Ceratopsyllus. 
+ This apparent articulation results, as I have ascertained, merely from the ex- 
tension of the inner membranous covering beyond the basal ccriaceous substance. 
{ Duges describes them as ‘Jisses ;” and Hooke, as each being a * single lens, 
like a cat’s eye.” Mr. Newman (Ent. Mag., No.11. p. 404.) mentions their simple 
construction as not having been noticed by any previous writer. 
§ In such cases they constitute the genus Ceratopsyllus Curt. I have, however, 
endeavoured to show that, from the variations of these organs in every species, it is 
not advisable to establish a genus upon this character. (Ent. Mag., No. 4.) 
