2 filaments at the apex of the abdomen, and from Cloeon by 

 havincr 4 wings. They may be advantageously formed into 

 two sections : 1st, those with wings very much reticulated ; 

 2nd, having very few transverse nervures, and these have the 

 wings ciliated in the Pseud-imago. 



Latreille and Leach describe the tarsi as 4-jointed, but 

 they are distinctly composed of 5 joints, and their singular 

 form as well as that of the claws is worthy of notice. 



This probably is an extensive family, and for a list of the 

 species I must refer to the Guide, and for the descriptions of 

 some new ones to the Lond. and Edin. Phil. Mag. 



As Linnaeus in his description of E. hioculata says nothing 

 of the number of the wings, it may not be a Baetis ; and as I 

 suspect his E. striata is the Pseud-imago of another species, 

 I have thought it better to adopt the one figured as the type. 



B. di.^par Curt. Brit. Ent. pi. 484'. c?. 



I have named this insect dispar from the little resemblance 

 that exists between the Pseud-imago and the perfect fly ; the 

 wings in the former have all the nervures suffused with fuscous 

 and the costa is not darker than the rest of the wing. 



On the 4th of June I found the Pseud-imago on White- 

 thorns near Ambleside, and on the following day I saw the 

 operation of shooting its skin : the thorax swelled and first 

 burst through, then by drawing up its body, it kept forcing 

 itself out, and being exhausted it lay dov^^n for a short period, 

 having the appearance of a Nympha, it then turned upon its 

 back, began struggling, soon gained its legs and walked on to 

 the gauze that covered the top of the box. 



The Plant figured is a species of Chara, new to Great 

 Britain, which differs from C. gracilis in its much smaller size 

 and in the denser and more tuft-like arrangement of the 

 branches. This addition to our Flora was pointed out to me 

 by Professor Henslow, in Bottisham-fen, during an excursion *, 

 and Professor Agardh, of Lund, who was present, pronounced 

 it to be his Nitella hyalina, the specific characters of which 

 we quote from his Systema Algarum: "Caule hyalino setaceo, 

 fructibus ad nodos in glomerulum congestis." This species, 

 from its great transparency and the comparative size of the 

 detached globules floating in the fluid contained in the stem, 

 is admirably calculated for exhibiting the circulation so con- 

 spicuous in this genus. 



* This very agreeable excursion was proposed and conducted by Professor Hens- 

 low with his accustomed kindness and liberality: it took place after the Meeting 

 at Cambridge of the Association for the Advancement of Science, and I am happy 

 in this opportunity of recording the pleasant day I spent with him on that occasion. 



