INTERNAL ANATOMY OF INSECTS. 121 
canal I shall notice, is the common harvest-man (Pha- 
langium Opilio) : in this, though the stomach and lower 
intestine are remarkably simple, yet their ccecal appen- 
dages are numerous and singular : the former, which 
has no distinct gullet, is pear-shaped"; and the latter, 
tapering downwards, and truncated at the end b ; con- 
nected with it above are no less than twenty-three cceca 
or blind appendages, of various forms and dimensions ; 
the last pair but one of which is very remarkable, being 
bent like a bow, and furnished externally with four short 
clavate processes c . It is probable that some of these or- 
gans are analogous to the bile-vessels of other insects. 
When the Creator in his wisdom fixed the limits of 
the various tribes of animals, he united them all into one 
harmonious system by means of certain intermediate 
forms, exhibiting characters taken some from those that 
were to precede, and others from those that were to fol- 
low them, and this not only in their external structure, 
but likewise in their internal organization; so that we are 
not to wonder if in the same individual we meet with 
organs that belong to two distinct tribes, or if, remaining 
nearly the same in their prima facie appearance, they be- 
gin to exercise neuo functions. An instance of this we 
have seen in the dorsal vessel of insects, which in the 
Arac/inida, though not materially different in situation 
or general form, by the addition of a small apparatus of 
arteries and veins becomes the centre and fountain of a 
regular system of circulation d . From the circumstances 
here alluded to, physiologists have been led to entertain 
a Ramdohr /. xxix./. 1*. A. b Ibid. and/. 3. B, D. 
c Ibid./. 2, 3. 5. &c. rt See above, p. 99—. 
