STATES OF INSECTS. (Larva.) 143 
form a fleshy protuberance, has on it a double series of 
rasps, as it were, consisting each of two rows of oblique 
oblong prominences ; and on the seven intermediate dor- 
sal segments there are also in the centre seven rasps of 
three or four rows each, of similar prominences: so that 
this animal at the same time can push itself along both by 
dorsal and ventral prolegs. It is worthy of observation, 
that a pair of these rasps is between the second and third 
pair of true legs. 
Diptera.—The larva of a little gnat, Chironomus ster- 
corarius*, drags itself along by the assistance of a single 
tubercle, placed on the under side of the first segment of 
the body, which the animal has the power of lengthening 
or contracting». That of another beautiful Chzronomus 
(C. plumosus), remarkable for the feathered antennz of 
the male*, has zwo short prolegs, or pediform but not 
retractile tentacula in the same situation*. Others, as 
that of Tanypus monilis, &c. have fwo pairs, one attached 
to the anal and the other to the first segment’. Tzpula 
amphibia De Geer in this state has ten prolegs, placed 
by pairs on the fourth, fifth,, eighth, ninth, and tenth 
dorsal segments‘; and Syrphus Pyrastri, one of the aphi- 
divorous flies, has not fewer than forty-two, arranged in 
a sextuple series, seven in each row §. 
It may not be useless to close this long description of 
the legs of larvee with a tabular view of them, founded 
* De Geer vi. 388. > Ibid. 389. * Reaum. v. ¢.v.f. 10. 
4 Tbid. 31. This larva has also a pair of pediform processes at the 
anus, surrounded at the end with claws (¢. v. f. 4, 5, s s), which he 
saw the animal use in locomotion; but which he suspects to be re- 
spiratory organs (Ibid. 33), which Latreille asserts they are. Gen. 
Crust. et Ins. iv. 249. 
© De Geer Ibid. ¢, xxiv. f. 15—17. f Tbid. 383, 
® Thid. 111. ¢, vi. f. 14—16. 
