AN VTOMY \M> I'll 



95 



Other lympanal organs, doublle^ and 'ind on the fore 



tibia- ol'Tet ligoiiiida-, anls, termites and 1'erlida-. on the femora .,j I'rdicu- 



lida- and the tai ne ( 'oleopt. -i 



Several types of chordolomil orpins have b hich 



those of the t ran-parent Corf///r</ larva mayser <-xampl< 



organs, situated on each side of abdominal segments 4-10, in<h. 

 con>i>t each Kitf. 140) of a tense cord, probably capable of vitXN 

 which is attached at its posterior end to the integument and at its 



n- 



FIG. 139. Inner aspect of right tympanal sense 

 organ of a grasshopper, Caloptenus italicus. b. chitin- 

 ous border; c, closing muscle of spiracle; gn, gan- 

 glion; m, tympanum; n, nerve; o, opening muscle 

 of spiracle; p, p, processes resting against tympan- 

 um; s, spiracle; tm, tensor muscle of tympanum; v, 

 vesicle. After GRABER. 



FIG. 140. Chordo tonal sense 

 organ of aquatic dipterous larva, 

 Corelhra plumicornis. cd, cord; eg, 

 chordo tonal ganglion; /, fibers of an 

 integumental nerve; g. ganglion of 

 ventral chain; /, ligament; m, lon- 

 gitudinal muscles; n, chordotonal 

 nerve; r, rods (nerve terminations); 

 /, tactile setae. After GRABER. 



anterior end to a ligament. Between the cord and the supporting 

 ligament is a small ganglion, which receives a nerve from the principal 

 ganglion of the segment. 



Vision. The external characters of the two kinds of eyes ocelli and 

 compound eyes have already been described. While the lateral ocelli 

 are comparatively simple in structure, consisting of a small number of 

 cells, the dorsal ocelli almost rival the compound eyes in complexity. 



Dorsal Ocelli. These consist (Fig. 141) of (i) lens, (2) vitreous 

 , (3) retina, (4) nerve fibers, (5) pigmcntcd hypodcrmis cells, and (6) 



