*5G'2 ORISMOLOGY. 
3. Unguiform Mandibles {Mandibulce ungui/brmes). 
The parallel claw-shaped mandibles of many Di- 
ptera. Plate XX. Fig. 1, 2. c'. 
4. Prop (Ercisma). A bipartite retractile glutinous or- 
gan exerted from between the legs of the genus 
S?nintkwus, and employed by the animal to sup- 
port itself when its legs fail it a . 
5. Fecifork (Fcucifurca). The anal fork on which 
the larva of Cassidcu, &c. carry their feces. Plate 
XVIII. Fig. 2. a. 
6. Mastigia (Mastigia). Two anal organs in the 
larvae of Centra Vinala, exerting from their apex 
a retractile flexible thread, with which they en- 
deavour, by lashing their sides, to drive away the 
Ichneumons. Plate XIX. Fig. 2. a. 
7. Syringes (Syringia). Organs situated in various 
parts of larva?, from which they ejaculate a watery 
fluid to annoy or drive away their enemies b . 
8. Rumules (Rumulai). Teat-like fleshy protube- 
rances observable on the bodies of various larvae c . 
9. Aeriducts (Aeriductus). Respiratory organs often 
foliaceous, with which the sides of the abdomen, 
the tail, and sometimes the trunk of aquatic larva? 
and pupae are often furnished. Plate XXIX. 
Fig. 3—7. 
10. Prolegs (Propedes). Fleshy exarticulate pediform 
often retractile organs, which assist various larvae 
in walking and other motions, but which disap- 
pear in the perfect insect. Plate XVIII. Fig. 
11, 12. b. 
« De Geer vii. 38—. /. \u.f. 10. rr. " Vol. II. p. 248—. 
c De Gecr ii. 507. t- xi./. 16. m. n. 
