) 



IS 



/ 1873.] 175 



I 



! among the herbage, or taking short flights. The smaller species fly in 

 calm weather more steadily and very slowly. Some are so abundant 

 as to be used for manui'e, and even for feeding pigs (!), on continental 

 ^ rivers ; and we are even told of shrubs being bent down by the multi- 

 tudes of an American species. Mr. Eaton has done good service by his 

 recent Monograph of the family, but very little is yet known of extra- 

 European forms. The sexes generally differ much in appearance, and, 

 owing to the fact of the final moulting being performed after the 

 winged condition has been assumed, it is thus necessary to have four 

 distinct series of each species, as Dr. Hagen observed in the ' Ento- 

 mologist's Annual' (1863, p. 6). When pinned, it is a matter of 

 indifference as to whether they be ' set ' or not ; the caudal setae are 

 very difiicult to retain entire, but this is best facilitated by pinning 

 A high, and not allowing these setae to come in contact with the drawer 

 gx or bos when dry. The true forms cannot be properly retained in dry 

 V specimens, and Mr. Eaton (see p. 5) advises that all be preserved 

 moist : altogether they are unsatisfactory insects from a collector's 

 point of view, and none suffer bo much from the attacks of the 

 apterous Psocidce. 



Stone-flies (Perlidce). 



Always found in the vicinity of water, and, as a rule, running 



\ water, the more rapid the better. Mountain streams are especially 



favourable ; and the larger s^jecies may be found among the herbage 



\ on the banks, or more readily under the large stones (sometimes par- 



J tially in the water) that lie on the edges of the burns. The species 



of the genus Pteronarcys (which is almost peculiar to North America) 



frequent the spray of waterfalls, and are furnished in the perfect 



state with external respiratory filaments, showing that their habits are 



even then so aquatic as to necessitate the extraction of air from water. 



The large species fly but little, yet are difiicult to capture, o"nang to 



their rapid sliding motion when alarmed ; the smaller forms (Leuctra, 



Ncmourn, &c.) fly in calm weather slowly, but moderately high, over 



the water. Some species (Nemoura) inhabit muddy ditches containing 



very little water, but the majority arc emphatically torrent-loving 



insects. All may be pinned and set out in the usual way, care being 



J taken not to break the caudal seta? of those larger forms that possess 



these organs ; and it is also necessary to be careful in spreading out 



the folded and delicate anal portion of the hind-wings : in re-setting 



i SWaxed specimens, this portion of the wing is extremely liable to get 



'■"mm. The whole family has no great amount of beauty to recommend 



it, but many of the forms are exti-emely curious, and comparatively 



