Auditory organs are best developed in such Insects as produce sounds as a call to each other. The Cockroach is dumb, and it is, therefore, not a matter of surprise that no structure which can be considered auditory should have ever been detected in this Insect.[121]
The sensory hairs of the skin have been already noticed (p. [31]).
CHAPTER VII.
The Alimentary Canal and its Appendages.
SPECIAL REFERENCES.
Cholodkowsky. Zur Frage über den Bau und über die Innervation der Speicheldrüsen der Blattiden. Horæ Soc. Entom. Rossicæ, Tom. XVI. (1881). [Salivary Glands of Cockroaches.]
Schindler. Beiträge zur Kenntniss der Malpighi’schen Gefässe der Insekten. Zeits. f. wiss. Zool., Bd. XXX. (1878). [Malpighian Tubules of Insects.]