ZOOLOGY. 713 



Arachnids. 



The hearing of Spiders. — No specialized organs that have beeii recog- 

 nized as having auditory functions have been certainly recognized in the 

 spiders. Some experiments lately conducted by F. Dald, however, con- 

 vinced him that the sense of hearing was not denied to those animals, 

 and he located it in certain hairs of the legs and palps. When sounds 

 were produced within reasonable distances of various spiders, their 

 actions, such as suddenly pausing when the sounds were made, although 

 the cause was not visible, rendered it evident that they took cognizance 

 of them. The only parts to which the evident faculty of hearing could 

 be attributed were two kinds of hairs arising from the legs and palps. 

 (1) One is of hairs of equal thickness throughout, fringed with a short, 

 fine pile toward the apex, implanted in cup-shaped depressions, and ex- 

 tremely mobile; a nerve is connected with the base of each one ; (2) the 

 other is of hairs set in rows and projecting outwards more than the or- 

 dinary protecting hairs. Objections may be urged to this theory, and 

 it may be thought that the hairs receive sensations of vibrations of the 

 web or of the motions of the air, but under a high magnifying power 

 they were found to be responsive to waves of sound, the hairs vibrating 

 when a note was sounding and resuming quiescence when it ceased. The 

 graduations in length of the hairs are supposed to indicate adaptation 

 to different notes, especially as their regularity in certain spiders of the 

 Epeirid family, which are claimed to be decidedly fond of music, is very 

 decided. Further, the author suggests that the arrangement of the 

 hairs is co-ordinal e with structural characters, and may, therefore, be 

 used in classification. His observations of German spiders furnished 

 two primary groupings : 



(1.) In the Epeirids and Theridiids the tibiae have two rows of audi- 

 tory hairs, the metatarsi single hairs and the tarsi "depressive, but no 

 projecting hairs." 



(2.) In the Saltids, Thomisids, and Lycosids the tibiae, metatarsi, and 

 tarsi have all two rows of hairs. 



The Tubitelarians exhibit intermediate conditions. (Zool. Anz., vol. 

 VI, pp. 267-270; J. E. M. 8. (2), vol. in, p. 652.) 



Insects. , 



Classification of Insects. — In connection with studies "on the classifi- 

 cation of the Linnaeau orders of Orthoptera and Neuroptera," Professor 

 Packard has reviewed the classification of all the Hexapods or the typical 

 insects and proposed a new arrangement for the subclass. He has es- 

 pecially "examined the fundamental characters of the head, thorax, 

 and abdomen, points neglected by most systematic writers." The out- 

 come has been to lead Professor Packard to separate the Neuroptera 

 from the Pseudoneuroptera, aud "to regard these two groups, with the 

 Orthoptera and Dermatoptera, as four orders of a category which may 



