June. 1921.] Cramptox: Evolutiox of the Anthropoda. 81 



insects. The so-called prosthcca of tlie mandibles of certain insects 

 is possibly the homolosue of the lacinia mobilis " Ji " of the mandible 

 shown in textfi^ure 4. and from the discussion tjiven above, it should 

 be evident that it is impossible to homologize the prosthcca or lacinia 

 mobilis of an insect's mandible with the lacinia of an insect's maxilla, 

 since the whole gnathol)ase. inclusive of the resjion from "/" to '" c," 

 of the scfjment forming the mandible shown in textfigure 4 is prob- 

 ably homologous with the whole gnathobase (or endite ) which forms 

 the lacinia of one of the segments entering into the composition of 

 the body of the maxilla of an insect. If entomologists could only 

 be brought to realize that the entire masticatory portion from " f" to 

 " c " of a mandible such as that shown in textfigure 4 represents 

 merely an area of one gnathobase (or endite) of one segment of a 

 limb such as " gb " of textfigure i. or " gh" of Fig. 20 (Plate VII). 

 and that the lacinia of the maxilla represents a similar entire endite 

 " gb " or '' c'l " of one segment of a limb such as that shown in Figs. 

 20 and 19, while the galea of the maxilla represents a second endite 

 " ri " of another segment of such a limb (the terminal portion of 

 the limb forming the maxillary palpus), there would not be such 

 absurd proposals put forward as some of the interpretations of the 

 parts proposed by Chatin.^ Smith. Packard, Hollis. Wood-Mason, and 

 others who have attemped to interpret the structure of insects' trophi 

 in terms of crustacean anatomy. 



The study of the modifications met with in the Crustacea has 

 amply repaid the time spent upon it. and I would emphasize the fact 

 that it is the Crustacea (not the Myriopoda) which have in each case 



1 Among other purely fanciful interpretations of the parts of the mandible 

 of insects, Chatin, 1884, refers to "' une ebauche de paipe " in the mandibles 

 of certain staphilinid beetles, apparently influenced by the suggestion of Hollis, 

 1871. who regards the prostheca of the mandible of certain staphylinids, etc.. 

 as the representative of the mandibular palpus of Crustacea. Wood-Mason. 

 18-9. has also developed the idea that the prostheca. or the lacinia mobilis of 

 beetles represents the endopodite of a nauplius limb (Crustacea), and Eaton, 

 1883. in his " Monograph of the Ephemerida " refers to the lacinia mobilis of 

 the mandibles of immature may-flies as the representative of the endopodite 

 of a formerly biranious limb. These and many similar misinterpretations of 

 the parts of the mandible clearly show that it is necessary to study the evolu- 

 tion of the mandibular appendage in CniM-ir. n in nrrb r to properly interpret 

 the parts of the mandible in insects. 



