ON GLANDS IN THE MAXILLAE OF TEGENARIA. 155 



meut at the base of the third joint. "When confined in a small 

 glass tube, these Spiders often move their palpi backwards and 

 forwards with a slight rotatory motion in such a manner that 

 the horny plate crosses the bands on the falces ; but hitherto I 

 have been unable, even with the aid of a microphone, to detect 

 sounds in connexion with these movements. 



The bands appear to be a modification of grooves which are to 

 be found on the falces, and which are similar to those already men- 

 tioned on the palpi, and are also present, without any specialized 

 form, on the falces of Linyphia clathrata, Lund, whose habits re- 

 semble those of the L. tenebricola, Wider. They are sufficient 

 to give an appearance of slight serration ; but up to the present 

 I have been unable to find any opposing surface which could be 

 used for stridulation in Linyphia clathrata. 



The absence of specialized stridulating-organs in most Araneae 

 does not, however, imply that they are mute. It is a common 

 practice with many to rub the falces against the maxillae ; and 

 were the serrated edge of these latter found in another part of the 

 body, similarly opposed to a hard toothed chitinous surface, it is 

 most likely they would be pronounced stridulating-organs. 



On certain Glands in the Maxillae of Tegenaria doniestica, Black- 

 wall. By F. Maule Campbell, F.L.S., F.Z.S., F.K.M.S. 



[Head June 17, 1880.] 



Dr. A. Was sm ann, in " Beitrage zur Anatomie der Spinnen" 

 (Abhandl. aus dem Geb. der naturwiss. Hamburg, Erster Band, 

 1846), and M. Felix Plateau, in his " Becherches sur la Structure 

 de 1'appareil digestif, et sur les Phenomenes de la Digestion chez 

 les Araneides dipneumones " (Bull. Acad. Boy. de Belgique, 

 ser. 2, t. xliv. 1877), describe a gland which is seated in the 

 labrum ; but the}*, like all other writers to whom I have referred, 

 make no mention of those which I am about to describe. In 

 the Tegenaria doniestica the apertures are on the inner side of 

 the median line of the upper face of each maxilla, where they 

 commence to incline towards the mouth, as seen in woodcuts 

 figs. 1 and 2, A. The external form consists of a ring (figs. 1 

 and 2, B), '005 millim. in diameter (average outside measurement) 

 in adults, enclosing a raised disk, in the centre of which is the 

 opening leading to a shallow cavity, from which runs the 



12* 



