90 Psyche [Jime 



crustacean shown in Fig. 5. In Fig. 14, Plate II, of a paper on 

 Anurida {IjM. B. C. Memoir No. XllI), an appendage of this 

 kind, borne near the tip of the ])aragnaths as in Apseudes (Fig. 5), 

 is figured in the "niaxillulK'' (i.e. the true paragnaths) of the 

 insect Anurida, by Imnis, 1U06 ; and in both insects and Crustacea, 

 these appendages of the paragnaths cannot possibly be honiologized 

 with the palpus, or terminal segments of the endopodite of the 

 limb forming the maxillula, or first maxilla. 



The principal points Ijrought out in the foregoing discussion may 

 be briefly summarized as follows. The great similarity between 

 the hypopharynx of insects and Crustacea lends additional weight 

 to the evidence of a very close relationship between these two groups 

 of arthropods, furnished Ijy a study of numerous other structures 

 of the Ijody as well; and since no such close correspondence in the 

 details of the parts of insects and chilopods exists, it is infinitely 

 more probable that insects Avere descended from crustacean-like 

 (instead of chilopod-like) ancestors. The "superlinguge" of insects 

 are completely homologous with the paragnaths of Crustacea, be- 

 cause they occupy exactly the same position, and have the same 

 form, structure, and function in the adult condition, and arise in 

 tlie same location, and in the same fashion, during embryonic 

 development in both groups of arthro})ods, thus fulfilling all the 

 requirements for establish.ing complete homology 1»etween the cor- 

 responding parts in insects and Crustacea. Since the paragnatlis 

 of Crustacea are not the maxillula? of Crustacea, it is folly to state 

 that the "superlingufe" of insects correspond to the maxillulw of 

 Crustacea, if they represent the paragnaths of Crustacea instead ; 

 and it is to be hoped that if anyone is unwilling or unable to inform 

 himself as to the truth in this matter, that he will at least refrain 

 from deceiving others by promulgating the misinformation that 

 the "superlinguae" of insects represent the maxillulne of Crustacea, 

 as though it were a demonstrated fact ! 



EXPLANATION OF PLATE V. 



Fig. 1. Posterior (ventral) view of mandible.s and hypopharynx of the 

 crustacean Ligyda. 



Fig. 2. Same of a nymph of the mayfly Heptagenia. The Inpoporus, or 

 salivary pore beneath the hypopharynx is not shown. 



Fig. 3. Posterior (ventral) view of the hypopharynx of the cru.stacean 

 Talorchestia. 



Fig. 4. Ventral (posterior) view of the sternum of the first maxillary seg- 

 ment, and the paragnaths of the crustacean Mysis. 



