20 fl. J. HANSEN. 



gin is convex, and on the upper side near the margin a pair of 

 very broad and very short i-ouiided lobes project freely over 

 theautero-lateral margin, and are a little removed from each 

 other at the middle. At the base of the hypopharynx its upper 

 side shows a transverse linear thickening, which is sinuate, 

 showing one unpaired and one pair of more lateral strong 

 curves turning backwards ; near the base of each lateral 

 curve is attached a long and strong narrow plate (tig. 1 d, j^-) 

 directed backwards, and these two plates are the inner 

 skeleton of the head also met with in lower insects, — for 

 instance, Hemimerus. From each outer angle of the middle 

 curve a chitiuous ridge proceeds forward and a little outward 

 supporting the hypopharynx. Outside each of these ridges a 

 maxillula (w.) is articulated in the lateral curve of the 

 transverse ridges ; this maxillula, which proceeds forwards and 

 somewhat inwards above the upper side of the hypopharynx, 

 is oblong, nearly equal in breadth, with the distal margin 

 cut off obliquely ; its wall is rather firmly chitinised in parts, 

 and the distal inner portion is submembranous, hairy, and on 

 the whole showing a structure like that often observed on a 

 lobe of a paired mouth-limb. I consider it to be absolutely 

 certain that these maxillulte do not belong to the hypo- 

 pharynx as "paraglossas ^' (Giassi), but that they are real 

 mouth-limbs homologous with the first pair of maxillae in 

 Crustacea and lower Insecta ; in 1893 I have (in 'Zool. 

 Anzeiger') given the name "maxillula)^' to these mouth- 

 limbs in the classes named. 



This not very detailed description of the mouth-parts must 

 be sufficient here; the figures will show several smaller 

 featnres not mentioned. A special comparison of the mouth- 

 parts of the Sympliyla with those in Thysanura, Diplopoda, 

 etc., shall be given in a future paper. 



