ANATOMY OF SPH^EOTHEETTJM. l7l 



head of Glomeris marginata. This is a horseslioe-'sliaped organ 

 lying beneath the eye ou either side of the head, and supplied by 

 a special nerve coming from the hinder part of the cerebral 

 ganglion. In the description of the plates he gives the following 

 account of it : — " . . . besteht aus einer hufeisenformig Vertie- 

 fung der Haut, von beiden Seiten durch vorspringende Eander 

 bis auf eine schmale Spalte geschlossen. . . . Yon Boden erhebt 

 sich ebenfalls ein hufeisenformig gebogener Wulst. Derselbe 

 dient zur Aufnahme eiuer gangliosen Nervenendigung." 



Lying within the antennary fossa, just beneath the eye, in 

 Sphtsrotherium, is a small round opening, surrounded by a 

 thickened rim of darkly pigmented chitin. This opening leads 

 into a small cavity, which seems to be lined with sensory epi- 

 thelium, and to be a sense-organ corresponding to the horseshoe- 

 shaped organ described by Leydig in Glomeris. This organ is 

 supplied, as in Glomeris, by a nerve springing from the hinder 

 part of the cerebral ganglion. The organ is enclosed between 

 two plates of exceedingly dense chitin, meeting at an acute 

 angle to form a ledge projecting over the antennary fossa, and 

 all my attempts to cut sections of it, or to make a preparation 

 fit for microscopical examination, failed. I tried several times, 

 but unsuccessfully, to dissect out the organ from the chitin that 

 surrounds it. 



I must therefore confine myself to pointing out the position of 

 the organ, and its homology with Leydig's organ in Glomeris. 

 My conviction is that these are true auditory organs. 



Unfortunately, as I am soon leaving England, I have not had 

 time to obtain living specimens of Glomeris and investigate 

 Leydig's organ with a view to determining its function. It will 

 not be out of place here to call attention to the fact that one of the 

 Chilopoda is known to stridulate *. The fact that this chilopod 

 does stridulate points to the existence of an auditory organ in at 



* Gerstacker (Stettin. Entom. Zeit. 1854, p. 312, Taf. ii. fig. 1) describes 

 in Euccvyhas crotakis, a chilopod, a sound-producing apparatus : thehindermost 

 pair of legs haye their fourth joints much enlarged find leaf-like, with their 

 edges raised and formed of hard chitin. When moving, and especially when 

 excited, these two laminar appendages are rubbed against one another and 

 thereby produce a rasping sound. It is curious to observe further that the 

 third joint on the inner side is produced into a process, and forms, with the 

 fourtli joint, a weak pincer-like apparatus, though Gerstacker does not state 

 that it has any such use. Etworybas is also a South-African myriapod, being 

 found at Port Natal. 



