1921] Crampton — Supcrlingme or Famglossa- of Insects 85 



communis, found in almost any pond, would have served equally 

 well for the purpose of comparing the "superlinguse" (paragnaths) 

 in the two groups of arthropods, but Ligyda has a large median 

 lohe, or lingua, which is not developed in Asellus, thus making it 

 somewhat easier to compare all of the parts under consideration, 

 in the two groups of arthropods (insects and Crustacea), and on 

 this account, Ligyda, rather than Asellus is here used for the pur- 

 pose of comparison. 



If the underlip and maxilla? of the mayfly naiad are removed, 

 as in Fig. 3, one may readily observe immediately behind, and 

 between, the mandil)les "md", a structure called the hypopharynx, 

 which is composed of a median, tongue-like lobe, the lingua, "li", 

 and a pair of lateral lobes, "pg", which the entomologists call 

 "superlingua?", or "paraglossffi" (a term which should be restricted 

 to the outer lobes on either side of the glossas of the labium). 

 Similarly, in the crustacean shown in Fig, 1, if the underlijD and 

 the two pairs of maxillre are removed, one may observe immedi- 

 ately behind, and between, the mandibles, "md", a hypopharynx 

 (exactly like that of the mayfly shown in Fig. 2) composed of a 

 median, tongue-like lingua, "li", and a pair of lateral lobes, "pg", 

 which the carcinologists call paragnaths. In the following discus- 

 sion, I have applied the carcinologists' term ]iaragnaths, to the 

 corresponding structures in insects, and I have applied the ento- 

 mologists' terms lingua and hypopharynx to the corresponding 

 structures in Crustacea, and allied arthropods. 



The a1)solutely patent correspondence between the parts of i\vi 

 hypopharynx of an insect (Fig. 2), and a crustacean (Fig. 1), 

 which is so simple and utterly obvious, that it should be evident 

 to anyone possessed of even the rudiments of a knowledge of 

 comparative anatomy, has apparently suffered through its very 

 obviousness and simplicity, for the human mind is apt to regard 

 the obvious with suspicion, as though it were a snare to entrap 

 the careless or undiscriminating ol)server, and to seek for subtler 

 analogies which appeal more strongly to tlie imagination, and 

 stimulate the speculative faculties. The unmistakeable resem- 

 blance between the hypopharynx of an insect (Fig. 2) and that 

 of a crustacean (Fig, 1), however, is not merely a superficial re- 



