1911.] NATURAL SCIENCES OF PHILADELPHIA. 415 



of the tactile hairs on the legs and palps auditory hairs, because they 

 responded to the vibrations of a violin. Wagner (1888) described 

 and gave drawings of four different kinds of hairs. His type called 

 the "poil tactil fin" seems to correspond very closely to Dahl's auditory 

 hair. Wagner showed that each type has a nerve fiber running out 

 from its base. He said that the function of these different types cannot 

 be recognized as identical and that no one of them can be regarded 

 as an auditory organ. But if their function is not identical, the 

 similarity of their fundamental parts as compared with each other and 

 with Dahl's auditory hair causes one to conclude that they have an 

 analogous function. Neither one of the above observers has seen the 

 sense cells or muscles of any one type of these tactile hairs. 



McCook (1890), in discussing the so-called auditory and tactile 

 hairs, thought that all the various types should be regarded as tactile 

 only and that perhaps each type has a particular tactile function to 

 perform, but not an auditory one as Dahl thought. 



Gaubert (1890) stated that the tactile hairs are moved by tur- 

 gescence and that they possess no muscular fibers. In (1892) he 

 asserted that the short curved spines of spiders are innately movable 

 and serve as a strong defense by projecting outward when the aranead 

 is seized. In discussing the blood pressure he stated that the joints 

 are stretched by turgor, which also moves the tactile hairs. 



Both Gaubert (1892) and Hansen (1893) have foundftactile hairs 

 in certain species of scorpions. The latter author described two 

 kinds of sensitive hairs in various species of the pedipalps, and tactile 

 hairs are found in all genera known to him in the pseudoscorpions. 

 Hansen and Surensen (1904), pp. 39 and 130) state that sensitive 

 hairs are present in the phalangids and ricinulei. 



Bibliography. 



Banta, A. M. 1907. The Fauna of Maj^field's Cave. (Pub. No. 67, Carnegu 



Institution, pp. 59-67.) 

 Bertkau, P. 1878. Versuch einer naturlichen Anordnung der Spinnen nebst 



Bemerkungen einzelnen Gattungen (Archiv. Naturg., p. 354). 

 1885. Bemerkungen zu Schimkewitsch's Xotiz (Zool. Anz., VIII, pp. 



537, 538). 

 Boys, C. V. 1880. The Influence of a Tuning-fork on the Garden Spider 



(Nature, XXIII, pp. 149, 150). 

 Campbell. 1881. Stridulating Organs in Spiders (J. Linn. Soc, XV, pp. 



152-155). 

 Dahl, T. 1883. Ueber die Horhaare bei den Araclmiden (Zool. Anz., VI). 

 1884. Das Gehor- und Geruchsorgan der Spinnen (Arch. mikr. Anat., 



XXIV, pp. 1-10). 



1885. Zur Anatomie der Araneen (Zool. Anz., VIII, pp. 241-243). 

 Gaubert, P. 1890. (a) Note sur les organs lyriformes des Arachnides (Bull. 



Soc. Philom., (8), II). (b) Quelque observations nouvelles sur le mouve- 



