42 THE ENTOMOLOGIST. 



It is noteworthy that in the female they hardly reach one-third 

 of the length of the spine formed by the third leg-cases, whilst 

 in the male they reach rather more than two-thirds. 



The wing apices are long and pointed, quite different to those 

 of the imago, and reach inwards behind the antennae to the 

 second pair of legs. The apex of the hind wing also appears 

 here, and is as pointed, and a little longer than the fore wing. 



The front of the last abdominal segments differ in the two 

 sexes in the usual way, the male having two eminences on the 

 ninth abdominal segment, whilst the female has a longitudinal 

 impressed line on the eighth. On the ninth, however, the female 

 structures are of a very unusual character. There are nine or 

 ten raised ridges, parallel and longitudinal, and the sharp edges 

 of the ridges are of dark (dense ?) chitin. Though straight 

 longitudinally, they have an antero-posterior curvature, such 

 that the set together look just like the upright iron bars placed 

 to protect windows, where the lower portions are bent outwards. 



It may be well to recapitulate that the larva is truly aquatic, 

 i. e. in water and wetted by it, in the first instar. Afterwards, 

 though under water, is aerial, i.e. surrounded by air in a case. 

 To compare it with the allied species, A.niveus and N.stratiotata 

 appear to be aquatic throughout. H. stagnata appears to be 

 aerial after hybernation, but I can find no definite statement on 

 the point. H. nymphceata is aerial ; I do not find any definite 

 statement that it is aquatic in first instar. It is the species 

 described by Reaumur, and often since as filling its case with 

 air, and the one that most readily occurs to us in thinking of the 

 group. At top of p. 2 I was thinking of nymphceata rather than 

 staynata, of which I was speaking. 



Explanation op Plate I. 

 Details of Cataclysta lemnata. 



Fig. 1. — Eggs, as laid under a leaf of Lemna trhulca, x 20. The 

 reproduction of photo (by A. E. Tonge, Esq.) fails to show the slight 

 sculpturing, but gives size, and shows method of laying, viz. border 

 to border, and not imbricated, as is usual in this sort of scale-like 

 egg- 



Fig. 2. — Diagram of one side of larva-skin, from medio-dorsal to 

 medio-ventral line, to show disposition of tubercles from first thoracic 

 to third abdominal segments. 



Fig, 8. — One mandible, much magnified, to show marginal teeth 

 supplementing the usual five, and forming a scoop ( x 160). 



Fig. 4. — Side view of pupa, x 3|. 



Fig. 5. — Portion of dehisced pupa, x 10, shows : — 1. Dorsal head- 

 piece, carrying (2) eye-cover. 3. Prothoracic cover, carrying (4) ventral 

 portion, that looks in pupa like maxillary palpus. 5. Mesothorax. 6. 



