FOLSOM : MOUTH-PARTS OF AXURIDA MARITBIA. 133 



be restricted ; while, for the dorso-lateral appendages, rejecting " para- 

 glosste," I propose the more appropriate name " superlinguae." 



The " gnathochihirium " of Syraphyla and Diplopoda may also prove 

 to be in part homologous with the hexapod labium. Having already 

 discussed the resemblances between the lateral portions of the gnatho- 

 chilarium and the first maxillas, I may compare the median components 

 with the labium. They were, in fact, designated " under lip " in Sco- 

 lopendrella by Grassi ("86% Tav. II. Figura 5). As in Apterygota, there 

 is a median portion and two stipal plates, each of which bears a papil- 

 late head, separated by a transverse suture. These are the only 

 points of agreement. On the contrary, the gnathochilarium is usually 

 homologized with the first maxillse of insects (Packard, '83^ p. 199 ; 

 Korschelt u. Heider, '90-93, p. 906) — apparently on account of Met- 

 schuikoff's ('74) researches. I can only suggest that the under lip of 

 Diplopods is anatomically of too compound a nature to be homologized 

 with the first maxillse only, and that we are not Avarranted in deriving 

 the entire lip from only two primary fundaments simply because Met- 

 schnikoff did. not allude to more than two. In ftict, Heymons ('97, p. 7, 

 Figur 2) has discovered a " post-maxillai-y " segment, without append- 

 ages, in the embryo of Glomeris ; but he regards it as equivalent to the 

 labial segment of insects. In other Diplopoda, for example Lysiopetalum 

 (Latzel, "84, Taf. IX. Figur 104) and Craspedosoma (Latzel, '84, Taf. 

 VI. Figur 72), the structure of the under lip is remarkably like that in 

 Scolopendrella. 



In Chilopoda there are two fleshy, jointed appendages (" first maxilli- 

 pedes," " zweites Unterkieferpaar "), which are conceivably equivalent, 

 in position only, to the second maxillae of Hexapoda, and are generally 

 homologized with the first pair of legs of Diplopoda. If the second 

 maxillae of insects are represented among Diplopoda in the manner I 

 have suggested, then the second pair of Chilopod " maxillipedes " 

 (" Kieferfusspaar ") corresponds with the first pair of feet of both 

 Diplopoda and Hexapoda, — a simple conception. 



The labium of Hexapods is homologous with the first pair of maxilli- 

 peds of Crustacea, according to the homologies which I have already 

 proposed for all the more anterior paired appendages. It is, then, erro- 

 neous to homologize with each other the second maxillce in these two 

 classes ; but the error is so firmly established that I have in this paper 

 frequently employed the term " second maxillae " for the labium of 

 insects, in order to avoid confusion. 



The evidence for my view of the homologies of the labium is of the 

 VOL. XXXVI. — >o. 5 4 



