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 a ; 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 new functions. An instance of this we 

 have seen in the dorsal vessel of insects, which in the 

 Arachnida, 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* 1 . From the circumstances 

 here alluded to, physiologists have been led to entertain 



3 Ramdohr t. xxix./. 1*. A. b Ibid. and/. 3. B, D. 



c Ibid.f. 2, 3, 5. &c. d Sec above, p. 99. 



