MOUTH-rARTS 3O9 



articulation — on each side of the labrum ; and even this pro- 

 jection is usually absent. Meinert recognised these projections as 

 mandibles in Smerinthus populi, and Kellogg in Protoparce Caro- 

 lina., another large Sphinx moth. They appear to be unusually 

 well developed in that group. In Castnia they are even more 

 definite than they are in Sphingidae. 



The Maxillae are chiefly devoted to the formation of the 

 proboscis. Their basal portions are anatomically very indefinite, 

 though they exist very intimately connected with the labium. 

 Each usually bears a small tul)ercle or a segmented process, the 

 representative of the maxillary palpus. The proboscis itself con- 

 sists of the terminal, or outer, parts of the two maxillae, which 

 parts are closely and beautifully coadapted to form the spirally 

 coiled organ, that is sometimes, though incorrectly, called the tongue. 

 The exact morphology of the Lepidopterous proboscis has not 

 been established. The condition existing in the curious family 

 Trodoxidae (see p. 4^2), where a prolwscis coexists with another 

 structure called a maxillary tentacle, suggects a correspondence 

 between the latter and the galea of a typical maxilla ; and 

 between the proboscis and the lacinia or inner lobe of a 

 maxilla : luit J. B. Smith is of opinion that the tentacle in 

 (question is a prolongation of the stipes. The condition of the 

 parts in this anomalous family (Prodoxidae) has not, however, 

 been thoroughly investigated, and Packard takes a different 

 view of the prol:)oscis ; he considers that " it is the two galeae 

 which become elongated, united and highly specialised to form 

 the so-called tongue or glossa of all Lepidoptera above the 

 Eriocephalidae." ^ The proboscis in some cases becomes very 

 remarkable, and in certain Sphingidae is said to attain, when 

 unrolled, a length of ten inches. In some cases the maxillary 

 lobes do not form a proboscis, but exist as delicate structures, 

 pendulous from the mouth, without coadaptation (Zeuzera aesculi, 

 the Wood-leopard moth). In other forms they are absent 

 altogether (Cossus, e.g.), and in Hepialus we have failed to detect 

 any evidence of the existence of the maxillae. On the other 

 hand, in Micropteryx the maxillae are much more like those of a 

 mandibulate Insect ; and various other Microlepidoptera approach 

 more or less a similar condition. In the genus last mentioned 



^ Amer. Natural, xxix. 1895, ]}. 637. It sliould be recollected that many 

 Lepidoptera do not possess any proboscis. 



