106 INTERNAL ANATOMY OF INSECTS.~ 
Eight bile-vessels are found in Myrmeleon, Hemerobius*. 
Fourteen sssssvssssssvsnesssseees Lormica rufa’. 
Baicnty sate. sthiesge0eis ai.oee larva sof Tenthredo Ame- 
ring ©. 
Manny « csssssccccrsesceerssseeees Libellulina,  Orthoptera, 
and Hymenoptera‘. 
The bile-vessels vary considerably in length: in many 
cases where they are, free they are short®; they are often 
very long, and perhaps those that are fixed 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 
small intestine and rectum, and not more than three pairs 
of fixed or united bile-vessels. In the Predaceous beetles, 
the gulict mostly widens at the base into a considerable 
crop, followed by a gizzard, a shaggy stomach, and two 
pairs of united bile-vessels. ‘The whole alimentary canal 
in these, is never less than double, and sometimes treble 
the length of the body£. In the carnzvorous beetles, at 
: Ramdohr Anat. t. xvil. f. 1,72.-6. > Tid. t. xiv. f. 3. 
© bid. t. xiii. f. 4. 4 Toid. t. xv. f. 3, 4. t.1. 7.1. 5. 9. t. xii. 
fA 5, 6, &e. * Ibid. t. xi. f. 4. t. xii. f. 4—6. #. xiii, f. 2--4, &e. 
 Thid, t. vii. f. 1. ¢. viii. f. 1, &c. 8 Ibid. t. ii. iti, xxv. 
