(Page 481) 

 The remarkable structure and slight movability of labium is pecu- 

 liar for Stenus . (cf. Fr. Meinert: The protrusile tongue in Steninerne , 

 m. 2 Tavl., Kbhvn. 1887). Its upper part, tongue-support, which at tip 

 bears the tongue with side-lobes and labial palpi (Fig. 145), is much 

 produced, but normally placed, and when reposing is crammed into a tube 

 of equal length, "tongue-sheath" (vagina linguae Mein.), of which the 

 lower part is anchored to the inner side of mentum; only the labial pal- 

 pi and side-lobes of the tongue are then visible. By a gentle pressure 

 on ventral side of the head the tongue-sheath can be produced, and si- 

 multaneously the insheathed labium is thrust out. When the pressure 

 ceases, both parts are again retracted. The test can be repeated often 

 without injuring the animal. When the animal is killed in poison jar, 

 it often in similar manner produces the labium and the entire tongue- 

 sheath not having time to retract it (see Fig 145). It is not improbable 

 that it, when alive and active can perform the same motion, which then 

 perhaps may be interpreted as a reflex action. 



Fig. 145. Head of a Stenus (ventral view) with produced labium. 

 g. (Jula. m. Mentum. a. Tongue-sheath, b. Tongue-support. 1. Tongue, 

 d. Side-lobes of tongue, p. lab. Labial palpi, p. mx. F/.axillary 

 palpi. 



(Page 482) 

 Pronotum is broadest at or before the middle, most often much nar- 

 rower than elytra, narrowing posteriorly and with oblique, non margin- 

 ated sides; elytra rarely shorter than metasternum; scutellum very small; 

 abdomen more or less tapering, more in the c than in the £ , most often 

 marginated, more rarely non-marginated and round, its first three-four 



•5- 



