interprelafion of Insedan & Myrio'podan Structures. 345 



expense of the endopodite (the exopodite is completely 

 lost), the endopodite becoming reduced to a three-segmented 

 mandibular palpus which is lost in many of the Crustacea 

 and in insects, while the spine-hke and tooth-hke processes 

 of the gnathobase region of the basal segment of the hmb 

 become modified to form the incisors of the mandible, or 

 unite to form the molar surface of the mandible. The so- 

 called lacinia mobihs of such a mandible is apparently 

 nothing more than certain broadened or fused hair-like 

 appendages forming the gnathofimbrium, or mandibular 

 fringe. I have taken up this feature in an article which 

 will shortly be published, and have referred to it here 

 merely to point out the fact that the mandible of an insect 

 such as Machilis, for example, represents only one single 

 segment of a hmb, while the parts of the maxilla which 

 form the cardo, stipes, galea, lacinia, etc., represent more 

 than a single segment of a limb (as I have pointed out in 

 another paper), and it is quite incorrect to state, as so 

 frequently is done, that the parts of the maxillae are re- 

 peated in the mandible of an insect. I have not been 

 able to find any indications of the cardo, stipes, galea or 

 lacinia in the mandible of any insect whatsoever, and the 

 statement that the parts of the maxillae are repeated in 

 the mandibles was apparently made without studying 

 the evolution of the structures in question from the trilo- 

 bites through a series of Crustacea such as that mentioned 

 above, to the lower insects such as Machilis. 



There are many other features of insectan anatomy 

 upon which a comparison with the structures of Crustacea 

 has thrown a flood of hght, such, for example, as the fact 

 that the cerci of insects (e. g. Machilis) represent the endo- 

 podites of the flagelHform uropods of such Crustacea as 

 Apseudes, or the fact that the styli of insects (and also 

 such modifications of the styli as the gonopods of male 

 insects, or the dorsal valvulae, etc., of the ovipositor of 

 the female insect) represenb the exopodites of the " swim- 

 merets " or their homologues in Crustacea ; but these and 

 similar points can be brought out more advantageously 

 in a series of articles, accompanied by suitable illustrations, 

 and taking up each phase of the subject in detail. The 

 foregoing article is therefore merely offered as a pre- 

 hminary note to point out the principal conclusions which 

 have been gained from a more extended series of studies 

 which will be pubhshed later. 



