STATES OF INSECTS. 145 



I should next say something upon the spiracles, or 

 breathing-pores, or any other external apparatus for the 

 purpose of respiration, in larvae ; but I think it will be 

 best to reserve the consideration of these for a subsequent 

 Letter. We will therefore conclude this detailed de- 

 scription of their parts in their first state, with some ac- 

 count of their other 



iii. Appendages. The generality of larvae have no other 

 external organs than those already described ; but in se- 

 veral of them we observe various kinds of retractile ones 

 and others — protuberances — horn-like processes — rays, 

 &c. ; which, though not properly coming either under 

 any of the above parts, or under the clothing of these 

 animals, yet require to be noticed. Upon these I shall 

 now enlarge a little. 



You must have observed upon the back of the last seg- 

 ment but one of the caterpillar of the silk- worm a horn- 

 like process, rising at first nearly perpendicularly, and 

 then bending forward. A similar horn, though confined 

 in the genus Bombyx to the silk-worm and a few others, 

 if we may believe Madame Merian, who, however, often 

 makes great mistakes, is found in the beautiful caterpillar 

 of one of the largest and finest moths that we know 

 (Erebus Stria: a ), the glory of the Noctuidce, and in most 

 of those of the hawk-moths (Sphinx F.) [$. Porcellus, Vi- 

 tis, and a few others excepted; in some of which, as 

 S. Labruscce, &c, this anal horn is replaced by a gibbo- 

 sity, and in others, as S. (Enotherce, by a callous eye-like 

 plate b ] in the same situation, but much longer c , and 



a Merian Ins. Sur. t. xx. b Ibid. t. xxxiv. 



c I have a caterpillar, I believe from Georgia, in which this horn 

 is nearly an inch long, filiform, slender, and tortuous. 

 VOL. III. L 



