HANSKX: OX SIX SI'KCIES OF KOKNEXIA. 205 



head of A. niirabilis : one organ (one coalesced pair of organs) 

 on the front and one on tlie lateral margin on each side above 

 the insertion of the palpi. H. and S. wrote: »Morphologically 

 they are hairs>^, but our description of them is not tjuite correct. 

 The two branches of the frontal organ look indeed very like 

 lancet-shaped, flat bodies, but they exhibit this shape ])oth when 

 seen from above and from the side, and therefore they must be 

 round. In A', mirabilis the lateral organ is apparently formed 

 as an oblong entire leaf, but in reality transverse sections must be 

 nearly circular. The branches of the frontal organ differ some- 

 what in length and thickness from species to species: they are 

 longer and more slender in A'. Grassii (pi. 4, fig. 3 b), while 

 they are shorter and thicker in A. angiista (pi. 3, fig. 3 a) than 

 in A", mirabilis. In A', mirabilis we find always only one single 

 lateral sense organ (one transformed hair), in A', chileiisis at 

 least two are present (pi. 3, fig. 2 a), in A'. Grassii (pi. 4, fig. 

 3 a), A', angusta (pi. 3, fig. 3 b) and A', siamcnsis I found 

 three, and in A'. Whcclcri (pi. 2, fig. 2 b) four organs. They 

 are always placed very close together, and to count them with 

 certainty is sometimes far from easy — it is best performed when 

 the head is seen obliquely from above, so that they project freely. 

 The organs in a group are always about of the same length 

 and shape. The organ in A. mirabilis is a little more to a 

 little lesser than two and a half times longer than thick, the 

 organs in K. Grassii are about six times longer than thick and 

 very acute (pi. 4, fig. 3 a), while the organs of the other species 

 exhibit a shape intermediate between that in the two species 

 mentioned. — The dift'erence between the species in the num- 

 ber of the lateral sense-organs seems to me to be very inte- 

 resting. 



b. Sensory hairs on the legs. In the previous paper 

 tactile hairs on the third pair of appendages — the first pair of 

 legs — are mentioned. These hairs originate from the bottom 

 of jar-like holes; they are very thin, nearly equal in thickness 

 from the base to the end, mostly considerably longer than the 

 other hairs and adorned with numerous exceedingly short, almost 

 invisible branches. We enumerated six hairs (on the sixth, se- 

 venth, ninth and eleventh joints); Grassi had found still another 



