BKITISH ODONATA IN 1913. 81 



It should be stated that the aquarium in which the 1912 

 nymphs were bred was standing on a brick window-sill, where 

 the window was open day and night all through the winter. The 

 weather being mild the water did not freeze, though it did in 

 former years. In fact a nymph of a larger species was on one 

 occasion frozen in the middle of a solid piece of ice and 

 remained so for two days. When the thaw came it revived and 

 seemed none the worse. These nymphs were not forced, there- 

 fore, by unusual heat, but probably were by receiving an 

 unnatural amount of food. As soon as they began to eat 

 Chironomus larvae, they were fed almost daily and when nearly 

 full-grown would sometimes eat as many as eight in succession, 

 though each was as long as the nymph itself. Probably in 

 confinement space has something to do with the rate of growth. 

 For a few kept in a very small bottle with abundance of food 

 scarcely grew at all, and when they were moved into a larger 

 aquarium, where food must have been more difficult to procure, 

 because less plentiful, they were found to be scarcely more than 

 half the size of some which had already been there for six weeks. 

 All emerged in the early morning, usually on dull days. One 

 nymph showed a particular aversion to sunshine. Being ready 

 to emerge, it crawled out of the water on a cloudy morning. 

 When on the wood the sun came out rather suddenly, and the 

 nymph immediately scrambled and fell down. As soon as the 

 sun disappeared it climbed up again ; but on the sun's reappear- 

 ance it repeated its previous performance. It did this three 

 times, and the nymph was not contented till the aquarium was 

 shaded, when it emerged none the worse for what had happened. 



Miss Molesworth's interesting notes may suitably be supple- 

 mented by a description* and figure (Plate II.) of a full-grown 

 nymph of S. striolatum, which I have therefore prepared : — 



Description. — General colour sepia, from very pale to quite dark. 

 Length, including anal appendages, about 18 mm. ; greatest breadth, 

 about 7 mm. Head of moderate size; in outline a flattened pentagon ; 

 width about 5-5 mm. Antennce of seven segments, the basal two 

 short and rather swollen, the rest more slender, with a ringed appear- 

 ance. Mask (labium) tapering backwards to the middle hinge where 

 it is narrow ; this hinge almost as far back as the insertion of the 

 midlegs ; extremity spoon-shaped, covering the face ; palpi broad, 

 where they approach one another and there serrated ; teeth reddish ; 

 movable hooks, long, sharp, slender ; centre of labium produced in 

 an obtuse angle ; on this lobe, internally, are two semicircles of long 

 reddish hairs, about fourteen in each, the lateral margin of each 

 palpus fringed with a similar row of hairs, pointing inwards. Several 

 pale marks in front of vertex, which also has pale markings. Eyes 



■'■ A figure of S. vulgatum (= striolatuyn) in W. H. Nunny's paper, 

 ' Science Gossip,' July, 1894, does not appear to represent a Sympetrum at 

 all, and is certainly not S. striolatum. 



