344 Dr. G. C. Crampton's Preliminary Note on 



4. The maxillulae of Crustacea develop in the location 

 typical of the other hmbs. The maxillae of insects also 

 develop in the location typical of the other hmbs. 



5. The maxillulae of Crustacea are distinct appendages 

 of a distinct segment. The maxillae of insects are distinct 

 appendages of a distinct segment. 



6. The maxillulae of Crustacea have a distinct neuro- 

 mere in the embryonic stages. The maxillae of insects 

 have a distinct neuromere in the embryonic stages. 



By comparing these two hsts of points together, it 

 will be seen that the maxillulae (first maxillae) of Crustacea 

 correspond in situation, form, function, structure and 

 development, with the maxillae of insects, and the super- 

 hnguae correspond in all of these points with the 

 paragnaths, while there is no such correspondence between 

 the maxillulae and the superhnguae. I would therefore 

 maintain that the superhnguae of insects are in every way 

 homologous with the paragnaths of Crustacea, and these 

 structures should therefore be called paragnaths in insects. 



Another absolutely unfounded and incorrect statement 

 which one encounters with disheartening regularity in the 

 zoological and entomological textbooks, is the absurd 

 statement that the primitively biramous condition of the 

 hmb of lower Crustacea is preserved in the highly modified 

 maxillae of insects. Thus the galea, etc., of the insect's 

 maxilla is supposed to represent the endopodite of such a 

 biramous hmb, while the maxillary palpus is supposed to 

 represent the exopodite. A comparison of the parts of 

 the maxilla of one of the primitive insects such as Machilis 

 vn\ih a series of Crustacean appendages, however, very 

 clearly indicates that the galea and lacinia correspond 

 to lobe-hke processes (sometimes spoken of as " gnatho- 

 bases ") of the basal segments of a hmb whose terminal 

 segments form the maxillary palpus, as embryology has 

 long shown is the case, and it is most astonishing that 

 such unfounded views could gain the widespread acceptance 

 which has been accorded them. 



If one will take the trouble to compare a series of hmbs 

 homologous "wdth the mandibular appendages of insects, 

 using the following sequence, (1) the trilobite Triarthrus, 

 (2) the Crustacean Nebalia, (3) the Crustacean Mysis, 



(4) the Crustaceans Asellns, Apseiides and Diastylis, and 



(5) the insect Machilis, he can readily trace the develop- 

 ment of the basal segment of the hmb which grows at the 



