3. P. cephalotes JSFob. 



4. bicaudata Linn., Fab., Panz. 71. 4. 



Thk insects of the genus now under investigation, like many 

 others belonging to the same order, live in the water till they 

 assume their perfect state, when they form a principal portion 

 of the food of fishes, especially trouts, and are consequently 

 well known to the angler. 



The following is a list of our British species. 



A. Abdomens very robust. 



1. P. grandis JVob. 



2. marginata Fab. — Panz. 71. 3. — 



flavipes Lat., Geoff. ? 



B. Abdomens slender. 



5. P. fuscipennis A^o6. I 7. P. viridis Pa6.— lutea ia^, Geoff. ? 



6. media Nob. | S. minor Nob. 



P. grandis is half as large again as the species figured, and 

 has been taken I have understood near the Croydon Canal. 



P. marginata. On the 4th of June Mr. Dale and myself 

 found a few specimens of this insect upon a species of fern 

 near Ambleside, and a few days after I took a considerable 

 number, lying three and four together concealed amongst the 

 foliage of the plant figured, as well as others that grew close 

 to the water's edge, also the exuviae attached to a fern. 



P. cephalotes. This species I found with the last ; and al- 

 though at first sight the two may be easily confounded, our in- 

 sect is distinguished by a much broader head ; the antennas 

 wings and setse in the males are not longer than the body, the 

 thorax is differently sculptured and transverse in the females, 

 and there are with very few exceptions two transverse nervures 

 on the disk of the inferior wings, which are always wanting 

 , in P. marginata^ the exuvia of the latter is beautifully macu- 

 lated, but in our insect it is entirely fuscous. The female 

 sometimes carries a globular bundle of little black shining ejjjjs 

 at the apex of her abdomen. These two insects are a favourite 

 food of the trout in Cumberland, and are succeeded by the 

 Bracken-clock [Anomala horticola), and that again I believe 

 by the Willow-fly (P. viridis). 



P. bicaudata is known by an orange stripe down the head and 

 thorax, and has been taken by Mr. Bracy Clark in Worcester- 

 shire, and in June upon Battersea britlge by Mr. Haworth. 



P. fuscipennis^ larger than P. viridis, with slightly fuscous 

 wings. This I took in Scotland. • 



P. media, the size of the last with yellowish wings and black 

 body, — beginning of June, on Oaks, &c., Ambleside. 



P. viridis, smaller, thorax with a black margin, body pale 

 with a black stripe. Beginning of June, upon Alders, New j 



Forest. — Reaumur believes figures 8, 9 and 10, pi. 14, to be I 



the larva? and their cases of a small Perla {pil. 13./ 12), which 

 is probably this or a congenerous species. 



P. minor, like the last, but only half the size ; found near 

 Ambleside, the beginning of June, running about in pairs, 

 whicli proves they are not males oi" P. viridis. 



TruUius europceus (Globe-flower) accompanies the insect. 



