406 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



endosternum ; and finally many parallel muscles, e, from the median 

 side of the stipes to the fulcrum. Inside the maxilla a long muscle, 

 /, is fanlike, originating from the lateral side of the stipes and running 

 to the lateral side of the lacinia; another, narrower, one, g, runs to 

 the galea ; a broad one (or rather two), h, connects the median side of 

 the stipes with the outside of the basis of the palpus ; and a small one, 

 i, connects this part with the distal part of the palpus. 



The maxilla of Collembola is also hollow at the inner and upper 

 side ; in the middle a rod bridges this cavity. Its anterior end is the 

 "Maxillenkopf " as it is called by Borner ; its very fine structures in 

 Tetrodontophora are drawn excellently by Borner (1908, Taf. VII, 

 fig. 12) and are alike in Onychiurus. It seems to be homologous with 

 the lacinia in Diplura. On the outer and anterior side of the stipes a 

 structure is found (drawn separately in fig. 10), which corresponds 

 to the palpus and galea. It is connected by a rod with the ligament 

 of the superlinguae ( ?). The cardo is very much like that of Diplura 

 and is placed dorsally to the lateral branch of the fulcrum. Denis 

 gives an interpretation of the collembolan maxilla which parallels 

 his views regarding Diplura. 



Figure 19 shows some important muscles, viz, from dorsally to 

 ventrally : Two muscles, a, running from the distal part of the stipes 

 to the hind wall of the head; two muscles, b, from the basal part of 

 the stipes and the distal part of the cardo to the middle of the head, 

 where they meet the ones from the opposite side below the oesopha- 

 gus ; further, c and d attaching a ligament from the lacinia to the stipes 

 and the cardo, respectively ; an oblique muscle, e, from the stipes to 

 the fulcrum ; two oblique ones, /, from the cardo and the stipes to the 

 fulcrum ; and two straight ones, g, from the stipes to the fulcrum. A 

 comparison with Denis's drawing of Tomocerus (1928, p. 163 — and 

 he himself says that conditions are identical in Onychiurus) would 

 give the following identifications: b = X, c = I, d—II, e—V, g — 

 VI+VII, f=VIII + IX. 



A comparison with Campodea shows the following points: The 

 muscle a in Campodea, running to the hind part of the head, is lack- 

 ing in Onychiurus, but the other two lacinial muscles correspond 

 (b and / in Campodca = d and c in Onychiurus) . The oblique and 

 straight muscles d and e in Campodea correspond to / and g in 

 Onychiw'us; and b in Otiychiurus — c in Campodea. 



The maxilla of Protura is hollow at the inner side ; the upper side, 

 in contrast to conditions in the other groups, is broader than the ven- 

 tral side. There is a cardo similar to that of the other groups. The 



