1 6 PBOCEEDINGS OF THE 



rubbing against a process between them. I have one here, wliich 

 is, however, not alive, but the mechanism of the sound-produc- 

 tion being still intact, and the body preserved in glycerine and 

 spirit, I think you will be able to hear the sound which these 

 curious creatures can produce when they are annoyed or dis- 

 turbed in any way. In life the crustacean would be found to 

 raise alternately first one and then the other antenna, and the 

 curious creaking sound is made. 



Unlike most Crustacea, in Palinurus the first joint of the 

 antennae (which may be distinguished by the opening of the 

 antennary gland, or kidney) is fused with the carapace and its 

 fellow of the opposite side. The second joint is closely articu- 

 lated with the first externally but loosely on its inner side. This 

 second joint has its upper and inner border prolonged to form a 

 semicircular chitinous disc, which firmly grasps the upper border 

 of a wedge-shaped process formed either by the antennulary 

 sternite or fused first joints of the antennae, and which lies be- 

 tween the antennae. This wedge-shaped process has its base 

 above, with its lateral smooth surfaces forming part of a circle, 

 of which the external point of articulation of the antenna is the 

 centre. Close to its lower or posterior border is a shallow 

 groove. The chitinous process of the upper border of the antenna 

 has an oval file-like surface on its inner side, the direction of the 

 teeth being that in which it is moved. The file is guided by a 

 tubercle at its proximal border that fits the groove. The direc- 

 tion of the teeth of the file corresponding with its direction of 

 motion is the exceptional feature referred to, there being appa- 

 rently a condition of minimum friction between the file aud 

 the surface on which it rubs. 



So far as I am aware, the sound-producing organ is in most 

 cases present in both sexes in Crustacea. 



Amongst Myriapoda, I only know of two examples possessing 

 sound-producing organs. In the male of SplicBrotlierimn, from 

 Madagascar, a chelate organ (not supposed to be an appendage) 

 IS situated on each side of the anal opening. It has a file on that 

 part which is in contact with the overlying tergum, this latter 

 being roughened by minute elevations against which the file rubs. 



The other case is that of Eucoryhas crotalus, from Natal ; in 

 this the three terminal joints of the last two appendages are 

 flattened out into leaf-like structures, which are said to produce 

 a sound either by being rattled together or upon the ground. 



In insects there are many cases in which, without special 

 structure, sound is produced by snapping the jaws, bringing 

 other parts suddenly together, or striking with the head, &c., 

 some resounding neighbouring body, as is the case with the 

 death-watch, &c. 



Many beetles are provided with a stridulating-apparatus, 

 present in both sexes : the file-surface is on the abdomen and 

 thigh in Loniaptera ; in Necrophilus two files on the abdomen 

 are rubbed by the elytra ; in Batocera a file on the metathorax 

 is rubbed by the mesothorax, &c. 



