142 DR. J. B. HICKS, FURTHER REMARKS ON 



mixed in a small bottle, with the addition of a little water when the effervescence is brisk, 

 will in a short time remove sufficiently the colour of most insects. Some parts which are 

 quite black, as the elytra of beetles, wings of bees, &c., require a day or two, and some 

 even a week. The hydrochloric acid has also a valuable jDroperty in rendering the nerve- 

 tubes more pei'ceptible. This plan of bleaching will be found invaluable in examining 

 the structm'c of antennae, which are often quite black, as I shall hereafter show. 



I have also shown the distribution of the nerve in the wing of Tenthredo viridls : the 

 bundle of nerves going to the vesicles was well marked in the specimen from which the 

 drawing was taken. 



These examples will, I think, serve to point out the intimate connexion between the 

 vesicles and the nerves. Whether the whole nerve be distributed, in all instances, to these 

 organs, I am inchned to doulit, since a small branch seems to pass beyond the point 

 where they cease. 



I shall now endeavour to trace these organs through the different tribes, so far as I have 

 been able. 



In the Symenoptera I find that they exist far more extensively than I supposed when 

 my former paper was read ; theu* detection has been mainly owing to the use of chlorine, 

 so few of this Order having light-coloured nervures in the wings. The figures here given 

 represent these organs in Ophion luteus (Tab. XXVIII. fig. 2) and Tenthredo viridis 

 (Tab. XXVIII. fig. 3), two species which are good examples of the tribe, and in which the 

 nervui-es are the most transparent. These organs in the Wasp {Vespa vulgaris), Honey- 

 bee {Apis mellifica), Andrena fulvicans, and Tenthredo lucorum, haviag a great resem- 

 blance to the above, I have not thought it worth whUe to figiu'e them. 



They consist of two groups on the upper, and one scattered group on the under side of 

 the subcostal nervure, amountiug in Ophion to 200-300 above, and perhaps 100 beneath, 

 \vith a smaller group at the end of the nervure. 



With regard to the Diptera I have nothing to add to my former remarks, excepting 

 that I have found the vesicles in Sippobosca equina distinctly marked both in the 

 halteres and wings. The diameter of each vesicle is 0-3^ iuch. 



In Tipula oleracea they are also well shown on the wings. 



In the Hemiptera they are very scanty; I have observed and drawn those on the 

 second wing of the Tree Bug, a species of Pentatoma. 



In Notonecta ylauca, or the Water-boatman, they are even more simple. 



In Corysus I have been unable to find them. I have carefully examined the elytra of 

 the common Bed-Bug ( Cme.r lectnlarius), but cannot find anything definite ; somepapiUse 

 occur on them, but they do not seem to be arranged in any distinctive manner. 



In the Coleopterovis group we find them highly developed, as may be observed in the 

 drawing of these organs in Strangalia elongata in Plate XXVII. fig. 1. 



They occur in numerous groups on the subcostal nervure, mostly at the widest part, 

 but are also scattered along it to the joint of the wing, where we find about ten or twelve 

 large vesicles in a group, after which they cease. 



In the Carrion Beetles (Necrophorus) they are very well developed, as also in Silpha, 

 where they are remarkably large, considering the size of the insect. 



