I . D. SOAK ; NOTES AND OBSERVATIONS ON 



a suitable host, in or upon which to locate itself for a long 

 Bhort period, according to the nature of the particular mite; 

 and as far as our observations have at present led us, this sup- 

 position is being extensively justified. 



We will take the genus Arrhenurus first. There is a figure in 

 tie' Journal of this Club, Series 2, Vol. 8, page 65, showing 

 a small fish which I found with two parasites attached. There is 

 also in the same volume, page 463, a note and some figures of an 

 Arrhenurus larva which was found living in the stomach of a 

 trout. But we are not sure if the mites were parasitic there, or if 

 tie' fish had just devoured a quantity of water-weed with attached 

 just at the point of hatching out. It was certainly a place 

 in which we did not expect to find the living larvae of water- 

 mi; Kreiidowsky in 1879 gave a drawing of a dragon-fly with 

 the wings covered with an Arrhenurus larva, which he savs is A. 

 papiUator, Mull. Last year, while at the Sutton Broad Laboratory, 

 the din ctor, Mr. Browne, allowed me to examine all his specimens 

 of dragon-flies. I found several with parasites, particularly 

 such dragon-flies as Agrion pulchellum and A. puella. These 



re often covered all over the thorax with a small, blue-coloured 

 Larva, which proved to be one of the Arrhenuri, and I should 

 think by the size and colour no other than Arrhenurus globator, 

 Midi. Plate 26, o,"shows Agrion pulchellum, Lind., with parasitic 

 larvae on the under-side of the thorax, and at p is the abdominal 

 portion of another dragon-fly, with the parasitic larvae on the pos- 

 terior segments. Figs, q and r are drawings of one of the larvae 

 detached. Lucas, in his monograph of British dragon-flies, 

 mentions one, Sympetirum meridionale, as being nearly always 



acked by a red acarus, so much so that its wings are tinted red 



by reason of the great numbers of these mites. Not being able 



tain one of these dragon-flies elsewhere, I went to the 



Natural Eistory Museum, where Mr. Kirby kindly allowed me to 



his representatives of this particular species. I found 



1 with parasites on the wings, and I have no doubt that 



y were the larvae of an Arrhenurus; but they were not in such 

 Qumbers as mentioned by Mr. Lucas. Possibly in the 

 com ervation a great many had fallen away. 



Tie' next genus which Las furnished us with a little information 



gards this interesting parasitic stage is the genus Hydrachna. 



is a fa i tlv large one. The various species seem to 



