SCIENCE-GOSSIP. 



(six species), Platetvum (one species), Libellula (two 

 species), and Orthetnim (two species). 



The second family — the Cordulidas — contains 

 one genus, viz., Cordulia (four species). 



The third family — the Gomphidae — contains 

 three genera, viz., Onychogomphus (one species), 

 Gomphus (two species) , and Cordidegaster (one species) . 

 The fourth family — the CEschnidse — contains 

 three genera, viz., Anax (one species), Brachytrou 

 (one species), and CEschna (six species). 



In this strong-flying group are included, as 

 might be expected, the majority (five) of our eight 

 chance visitors, the remaining three belonging to 

 the genus Lestes, two of these, however, being of 

 very doubtful authenticity. It is in this group, 

 too, that we may chiefly hope for additions to our 

 list, Dr. Hagen enumerating fifteen species likely 

 to occur here, and only three in the second group. 

 Allied species in this group are very difficult to 

 distinguish on the wing, while all, from their strong 

 flight and from their habit of flying over water, are 

 so difficult to catch, that strangers might well escape 

 detection. Thus, in 1892, at Wisley, while filling 

 up my series of CEschna cyanea, I took two CE.juncea, 

 and not until after they were dead had I any idea 

 of the value of my captures. CE. mixta is doubt- 

 less passed over in a similar way. 



Watch a Libellula or an CEschna leisurely swing- 

 ing along the edge of a pond, so quietly and so 

 steadily that it seems easy to catch him, even in a 

 hat ; but try, not with your hat, even with your very 

 biggest net, and you will find that, carefully as you 

 have watched him, he has as carefully kept his 

 eye (or a few thousand of the facets of his eye) on 

 you, and is just half-a-foot or so beyond your 

 utmost reach, and, except by stratagem, his capture 

 is a process requiring considerable time and 

 patience, or luck ; while the thoughts of the 

 would-be captor if uttered — and they often are 

 uttered — need the kindliest services of the Record- 

 ing Angel. Yet I know no entomological triumph 

 more deep or more complete than that of captur- 

 ing, say, an Anax formosus after an hour's watchful 

 patience, or a frantic and exhausting chase. 



There is much, too, still to be learned of their 

 habits. Thus, one day in 1893, at Wisley, Cordulia 

 cenea was fairly common, yet I have never seen it 

 there before or since, often as I searched. Where 

 had they gone, and why ? 



The second group, the Calopterygina, or 

 Agrionina, contains the slow-flying, slender-bodied 

 species, though sometimes both species of 

 Calopteryx seem taken with a taste for wandering, 

 and then fly nearly as fast as a Vanessa butterfly, 

 but as a rule their flight is as feeble and hovering 

 as the others in the group. There is probably no 

 more beautiful entomological sight than a number 

 of either or both of these species (for sometimes, 

 though not often, they may be taken in company) 



slowly flitting about on a still bright morning, their 

 wings gleaming and sparkling in the sunshine, 

 resembling rather denizens of an exotic region 

 than inhabitants of our own northern clime. 



The beautiful blue Agrions, too, have a special 

 charm of their own ; but their beauty fades almost 

 with their lives. No one has yet learned how to 

 preserve even a trace of their brilliant colouring. 

 This group of Agrions contains two families, seven 

 genera, and seventeen species. 



The first family — the Calopterygidae — contains 

 but one genus, Calopteryx (two species). 



The second family — the Agrionidse — contains 

 six genera, viz., Lestes (six species), Platycnemis 

 (one species), Erythromma (one species), Pyrrhosoma 

 (two species), Ischium (two species), and Agrion 

 (four species). 



Of these Lestes sponsa, Ischium elegans, Agrion 

 puella, and A. cyathigerum, are universally abundant, 

 and A . pulchellum, though somewhat more local, is 

 nearly equally common. 



Wherever these species occur, they may be often 

 seen in countless swarms, rising in hundreds from 

 the reedy edge of a pond or sluggish stream, 

 attracting even unentomological eyes by the 

 extreme charm of their beauty. 



Unlike many insects, dragonflies revel in the 

 hottest sunshine, and rarely move under other 

 conditions (with the exception of CE. grandis, which 

 occasionally flies at dusk). The "memory of them 

 is always associated with those bright and sunny 

 days that, from their comparative rarity in England, 

 stir the pulse and gladden the heart, not only of 

 the entomologist, but of every lover of nature. 

 55, Lincoln's Inn Fields, London; Feb,, 1894. 



Great Auk's Egg. — Mr. Henry Stevens, at his 

 Auction Rooms, King Street, Covent Garden, on 

 Thursday, 22nd February, sold an egg of the great 

 auk. It formerly belonged to Mr. Yarrall, later-to 

 Mr. F. Bond, and last to Baron d'Hamonville. Sir 

 Vauncey Crewe, Bart., was purchaser at /315. 



Circulation in Plants. — Can any ot your 

 readers kindly tell me the way to view circulation 

 of sap in plants ? I have often tried, but failed. I 

 believe it ought to be seen well in the hairs of the 

 common stinging-nettle ; and there must surely be 

 many plants in which it is to be seen. I want to 

 know what plants I might try — what objective I 

 should use — what illumination is required, whether 

 very powerful or not, and how long after cutting the 

 specimen does the circulation last ? Doubtless 

 many others would be glad of this information. — 

 A. C. Smith, Crowboro, Sussex. 



