50 THE COCKROACH : 



the tip, and through them the juices of the prey are sucked into 

 the mouth, which has no other opening. The labium undergoes 

 marked adaptive change, without great deviation from the com- 

 mon plan, in the "mask" of the larva of the Dragon-fly. This 

 well-known implement has a rough likeness, in the arrangement 

 and use of its parts, to a man's fore-limb. The submentum 

 forms the arm, the mentum the fore-arm. Both these are 

 simple, straight pieces, connected by an elbow-joint. The hand 

 is wider, and carries a pair of opposable claws, the paraglossoo. 

 In some Coleoptera the labium is reduced to a stiff spine, while 

 in the Stag-beetle it is flexible and hairy, and foreshadows the 

 licking tongue of the Bee. The maxilla; become long and hairy 

 in flower-haunting Beetles, and even the mandibles are flexible 

 and hairy in the Scarabocus- beetles. Fritz Miiller has found a 

 singular resemblance to the proboscis of a Moth in a species of 

 Nemognatha, where the maxilloc are transformed into two sharp 

 grooved bristles 12 mm. long, which, when opposed, form a 

 tube, but are incapable of rolling up.* 



In the Honey Bee (fig. 23) nearly all the mouth-parts of the 

 Cockroach are to be made out, though some are small and others 

 extremely produced in length. The mandibles (Mn) are not 

 much altered, and are still used for biting, as well as for knead- 

 ing wax and other domestic work. The mandibular teeth have 

 proved inconvenient, and are gone. The lacinia of the maxilla 

 (Mx l ) forms a broad and flexible blade, used for piercing succu- 

 lent tissues, but the galea has disappeared, and there is only a 

 vestige of the maxillary palp (J/lr/j). In the second pair of 

 maxillae the palp (Lp) is prominent; its base forms a blade, 

 while the tip is still useful as an organ of touch. The para- 

 glossse (P(() can be made out, but the Iacinia3 are fused to form 

 the long, hairy tongue. This ends in a spoon-shaped lobe (not 

 unlike the "finger" of an elephant's trunk), which is used both 

 for licking and for sucking honey. 



The proboscis of the Bee is therefore more like a case of 

 instruments than a single organ. The mandibles form a strong 



O O o 



pair of blunt scissors. The maxillae are used for piercing, for 

 stiffening and protecting the base of the tongue, and when 



* Ein Klifer mit Schmetterlingsriissel, Kosmos, Bd. VI. We take this reference 

 from Hermann Muller's Fertilisation of Flowers. 



