PECULIAR SENSE ORGAN IN SCUTIGERA COLEOPTRATA. 255 
into the chitinous lining of the pouch and indeed projects for 
a short distance on the inner side of the latter. The outer end 
is prolonged into a long fine hair. 
General Features of the Internal Anatomy. 
The hypodermic layer of cells or matrix lying beneath the 
exoskeleton accompanies the chitin round the lateral recesses, 
and at the edge of the folds which form the lateral lips of the 
two pouches becomes continuous with a thick layer of sensory 
epithelium which lines the greater part of the two pouches 
(fig. 2, s. e.). On reaching the dorsal lips of the pouches, which 
lips bound laterally the median recess, the epithelium loses its 
sensory character and again becomes simple hvpodermis. On 
the dorsal part of the median recess the epithelium again 
becomes sensory in character. The nerve supply is furnished 
by two short thick nerves (fig. 2, N.) which arise from the front 
portion of the suboesophageal ganglion. The two nerves enter 
the sensory epithelium, one to each pouch, near the posterior 
part of the organ, and there breaks up into a number of fibres 
which become lost in the epithelium. The form of the organ 
as indicated by the division into two pouches (fig. 2, p.) and 
the double nerve supply seem to me to show conclusively that 
it is double, and that each of the two pouches with its other 
parts is to be regarded as constituting a separate sense organ. 
Histology. 
The histology of the cellular tissues demands a more detailed 
account. The cells forming the matrix from which the 
exoskeleton is renewed after each moult are large, rather 
columnar in their character, and have a well-defined nucleus. 
They are closely applied to the chitin and accompany it up to 
the end of the lateral recesses (refer to fig. 3, hy .) where the 
folds forming the ventral lips of the pouches begin. Here the 
chitin is thrown into folds somewhat like those which charac- 
terise the surface of the pouches. The hypodermic cells here 
lose their regularity of outline and follow the chitin into the 
