86 Psyche [June 



semblance calculated to decei^'e the unwary, since the h^'pophar^mx 

 in the two groups not only occujnes the same position, and has 

 the same form and structure in both insects and Criistacea, but it 

 also has exactly the same em1)ryological development, and serves 

 the same function (i. e., that of a secondary underlip, provided 

 with taste organs, etc.) in both groups — and what more could one 

 ask, to establish complete homology? I would therefore maintain 

 that the so-called "superlingua?" of insects do not represent the 

 maxillulse or first maxillse of C'rustacea, since they do not occupy 

 exactly the same position, they do not exhibit the same form and 

 structure, they do not have exactly the same embryological develop- 

 ment, and they do not have exactly the same function in the two 

 groups; and I would claim that the so-called "superlingUcTe" of 

 insects most emphatically do represent the paragnaths of Crus- 

 tacea, since they agree with these in all of the features mentioned 

 above. 



Since the "superlingua?" of insects represent the paragnaths of 

 Crustacea, l)y comparing the higher Crustacea, which are near 

 insects, with the lower Crustacea, which approach the trilobites and 

 other primitive arthropods, we are able to trace the evolution of 

 these structures, and to determine their morphological significance. 

 In Ligyda (Fig. 1) the paragnaths, "pg", are rather closely asso- 

 ciated with the median lingua, "li", which appears to be formed as 

 a f)rojection of the pharyngeal ridge, "pe", behind it, which appar- 

 ently includes in its composition a portion of the sterna of certain 

 of the mouthpart segments. In Talorchestia (Fig, 3) the lingua, 

 ^'li", is represented by a double ridge, or lobe-like projection of the 

 median pharyngeal ridge, "pc"; and it would appear that the 

 median, basal portions of the paragnaths, "pg", likewise take part 

 in the formation of the lingua, "li", so that the lingua of higher 

 Crustacea and insects may be formed in part by the paragnaths, 

 although the greater part of the lingua is probably formed by por- 

 tions of the sterna of certain of the mouthpart segiuents, as is 

 indicated by embryology. On either side of the median pharyn- 

 geal ridge, "pc", of Figs. 1 and 3, are rib-like structures, "tc", 

 which are located at the base of the tro]ihi or moutli parts. It is 

 possible that the lingual lorae, "11", of Figs. 2 and 8, represent 



