112 INTERNAL ANATOMY OF INSECTS. 
Two bile-vessels are found in the larva of Cetonia aura/a 3 . 
Four most Coleoptera, Diptcra, 
and Hemiptcra b . 
Six Lepidoptera, some Coleo- 
ptera c , &c. 
Eight Myrmeleon, Hemerobius 6 . 
Fourteen Formica rufa e . 
Twenty larva of Clavellaria Ame- 
rincB f . 
Many Libellulina,Orthoptera, and 
Hymenoptera e . 
The bile-vessels vary considerably in length : in many 
cases where they are free they are short h ; they are often 
very long, and perhaps those that arejixed may be gene- 
rally stated as the longest. In the Lamellicorn beetles 
they are remarkable for their great length '. 
Having given you this general account of the intesti- 
nal canal and its parts and appendages, I shall now state 
some of the peculiarities that in this respect distinguish 
particular tribes and families. 
The Coleoptera alone, exhibit as many variations in 
the structure of the alimentary tube as all the other Or- 
ders of insects together : — to particularize these would 
occupy too large a portion of this letter, I shall therefore 
only notice a few of the most remarkable. In general 
they may be stated as having universally a stomach, a 
» Ramdohr, t. vii./. 2. b Ibid. t. ii. iii. &c. t. xx. /. 1, 2. 6. 
t. xxii./. 1—5. &c. c Ibid. t. xviii./. 1.5.*. iv.f. 1. See 
also t. \lf. 1. 3. d Ibid. Anat. t. xvii./. 1, 2. 6. 
e Ibid.t.x\v.f.3. l Ibid. t. xiii./. 4. 
s Ibid. t. xv. / 3, 4.*. 1./. 1. 5. 9. t. xii./. 4, 5, 6, &c. 
h Ibid. t. \\.f. 4. t. xii./. 4—6. /. xiii./. 2—4, &c. 
; Ibid. t. vii./ 1. 1. viii./. 1, &c. 
