PECULIAR SENSE ORGAN IN SCUTIGERA COLEOPTRATA. 257 
Conclusions. 
The active predatory habits of this Myriapod and its power 
of swift locomotion would seem to render well-developed sense 
organs a necessity to it ; in fact it has facetted eyes in place 
of the simple eye-spots of most Myriapods. 
The organ above described must, I think, be included among 
the great number of widely dissimilar organs usually classed 
together as auditory, and may be compared to the tympanic 
organ of insects. 
The auditory organs of insects have been investigated prin- 
cipally by v. Siebold (‘ Archiv fur Naturg./ 1844), Leydig 
(‘Muller’s Arch./ 1855 and 1860), v. Hensen (‘Zeitschr. f. 
wiss. Zool./ tom. xvi, 1866), and v. Graber (‘ Deutschr. der K. 
Akad. der Wissensch./ Wien., 1875). The tympanic organ of 
the Acridiidae consists essentially of a tympanic membrane sup- 
ported by a chitinous ring. Places in the tympanic membrane are 
thickened, so as to form solid chitinous pieces of peculiar form, 
the internal surface of which is covered with indentations in 
which the extreme ends of the sensory apparatus end (Fr. 
Leydig, ‘ Muller’s Archiv,’ 1855, p. 401). The auditory nerve 
spreads out on these chitinous pieces and forms a ganglion, 
from which fibres ending in peculiar sense cells are given off. 
A trachea lies close to the ganglion internally to it, and not 
unfrequently swells to a vesicle. 
On comparing the organ of Scutigera with such an organ 
there is found to be a great similarity in the general plan. 
Each pouch in Scutigera represents the insect tympanum. 
In both cases we have a thick nerve breaking up into a number 
of sensory elements, which end in depressed spaces in the 
chitinous membrane. W T ith regard to the chitin hairs which 
project through the chitin in Scutigera, I think it will be 
worth while to consider Hensen’s investigations on the auditory 
rods of insects (Horstrifte, v. Hensen, 1. c.). He makes an 
interesting comparison between these structures and the audi- 
tory hairs of the crustacean auditory sac, and draws the con- 
