HANSEN: EXTERNAL SENSORY ORGANS IN ARACHNIDA. 243 



eral statements as to their number and occurrence on the 

 joints mentioned in various famiHes and some genera, showing 

 that their number and arrangement afford characters of 

 systematic value, but yet without carrying out the investi- 

 gation of a really sufficient number of forms. — In an in- 

 teresting paper (in 1888) W. WaGNER divided the tricho- 

 bothria in Araneae into two types, with a detailed account 

 of their structure, especially as compared with that of other 

 sensory hairs and purely protecting hairs in Araneae; in 

 chapter V a more detailed account of Wagner's results is 

 given. 



In the orders Solifiigce, Opiliones, and Ricinulei (Crypio- 

 steinma) trichobothria are entirely wanting. — • I am not 

 acquainted with most of the vast literature on the Acari, but 

 as far 1 know trichobothria are unknown in this extremely 

 rich order. 



B. Sensory Hairs not projecting from real calicles. 



In Scorpions no other sensory hairs than the tricho- 

 bothria are known. In the Chelonethi there exists on the 

 lower side of the hand of the small chelae (antennae), a seta 

 or generally a row of setse, which has been named the 

 flagellimi. These hairs differ considerably as to serrulation 

 or pubescence, thickness, and number in various genera (see 

 f. inst. H. J. Hansen a, pis. IV — V), but -it seems to me 

 somewhat uncertain whether they are a kind of tactile hairs, 

 as the nerve has hitherto not been pointed out, and in no 

 respect they are similar to real sensory hairs in other Arach- 

 nida. In 1893 (H. J. Hansen a, p. 215—217) I critisized 

 severely SteCKER's fanciful description, figures and interpre- 

 tation; Stecker, who later on created for himself a somewhat 

 Herostratian celebrity in Zoology by his invention of the not- 

 existing animal Gibocelhnn, interpreted the flagellum as an 

 olfactory organ, and has mc)st unfortunately been taken 

 seriously by SlMON, GaUBERT and CronebeRG. 



In the Pedipalpi very small tactile hairs of peculiar shape 

 are found on the distal part of first pair of legs, which always 



