34 



HARD WICKE'S SCIENCE-GOSSIP. 



takes the form of a ribbon, attached by one of its 

 edges to some submarine body. Those of the 

 Bulimus might be taken for a humming-bird's egg. 

 The eggs of the great Achatina exceed an inch in 

 length, and have a calcareous shell. The tropical 

 Bulimi cement leaves together, to protect and 

 conceal their large bird-like eggs. The slugs bury 

 theirs in the ground ; the oceanic snail, Jauthina, 

 attaches them to a floating raft, and the Argonaut 

 carries them in her frail boat. In some marine 

 species the eggs are enclosed in leathery capsules, 

 which are often united in a large mass ; each capsule 

 contains numerous eggs. The horny capsules of the 

 whelk are clustered in groups, with spaces pervading 

 the interior, for the passage of sea water. The 

 nidamental ribbon of the Doris and Eolis is attached 

 to a rock, or some solid surface, from which it will 

 not be detached by the waves. 



The periwinkle lays an immense mass of eggs 

 larger than its own shell. In bivalves the eggs are 

 usually like spawn, and generally retained by the 

 mother. The ovaries of the Brunnion, a snail without 

 shell, are eaten in Nice. 



The eggs of the Octopus we are told, when first 

 laid are small, oval, translucent granules, resembling 

 little grains of rice, and not quite an eighth of an inch 

 in length. They are attached to a common stalk, to. 

 which every egg is separately attached, as grapes form 

 part of a bunch. Each of these clusters contains 

 about one thousand eggs, and a large octopus will 

 produce forty- thousand to fifty-thousand. 



The Pyrnla lays a long string of egg-cases, each 

 containing from fifteen to twenty eggs, or sometimes 

 more. 



The eggs of the king crabs (Limulus gigas and 

 L. moluccanus), which are collected in large quantities, 

 among other places on the north coast of Java, are 

 considered a delicacy by the natives and are eaten 

 both fresh and salted, as the spawn of the lobster is 

 here. 



DRAGON-FLY GOSSIP. 



By W. Harcourt Bath, Author of "An Illustrated 

 Handbook of British Dragon-rlies," " A Label List 

 of British Dragon-flies, " etc., etc. 



{Continued from p. 206.] 



Swift preying upon Dragon-flies. 



WHILE hunting for dragon-flies near Bourne- 

 mouth in August 1890, I saw a swift 

 (Cypselus apus) flying over a pond in pursuit of small 

 Odonata, including Lestes spo?isa and various species 

 of Agrions. Some boys informed me that a few- 

 minutes before my arrival they had witnessed the 

 same bird capture and devour a very large dragon- 

 fly, which I think from their description must have 

 been a specimen of ALschna cyanea. 



It is well known that swallows, and sometimes 

 sparrows, feed upon the smaller species of dragon- 

 flies. I shall be glad to know what other kinds of 

 birds readers have seen to prey upon these insects in 

 this country. I have read somewhere that the kestrel 

 possesses a predilection for prey of the kind in 

 question. 



A Veteran Dragon-fly Hunter. 



Mr. Robert Calvert of Bishop-Auckland, whose 

 death was recorded last year at the age of seventy- 

 one, was a veteran dragon-fly hunter, and one of my 

 first correspondents concerning^the Odonata. 



Some years ago, in response to an appeal in the 

 " Entomologist," he sent me a list of the dragon-flies 

 occurring in his neighbourhood. He wrote: " They 

 were fifty years since much commoner than they are 

 now, partly owing, perhaps, to an enormous increase 

 in population ; but chiefly, I think, to the pollution 

 of all our streams by colliery operations. Some of 

 my specimens are very old ; it is fifty years since I 

 took some of them, but they have kept their colour 

 well." 



Mr. Calvert, I may remark, is the authority for 

 several localities for dragon-flies in my "Illustrated 

 Handbook." 



Does any reader of Science-Gossip know what 

 has become of this gentleman's collection ? 



Dragon-flies in Dry Seasons. 



There is a circumstance connected with the abun- 

 dance of dragon-flies in dry summers which I have 

 hitherto been unable to elucidate to my complete 

 satisfaction. In many places in the South of England, 

 particularly on chalky soils, there are very few 

 streams, and the dragon-flies, for the most part, 

 undergo their metamorphoses in small artifical ponds, 

 or clay-pits, which dry up entirely in hot weather, 

 although the insects do not appear by any means to 

 diminish in abundance in consequence. 



On Parley Heath, in Hampshire, where dragon- 

 flies are very plentiful, the numerous clay-pits to be 

 met with there regularly become dry during nearly 

 the whole of the summer. 



What I should like to know therefore is what 

 becomes of the dragon-fly larvae and pupas, which 

 have not arrived at maturity when this state of things 

 overtakes them, and also where are the ova deposited 

 by those dragon-flies which have acquired the winged 

 state, if there is no water to receive them ? 



I can only surmise that the larvae and pupae, in the 

 event of the drying-up of a pond, bury themselves in 

 the mud, after the fashion of certain kinds of fishes 

 in India, breathing by the same means, and returning 

 again to activity on the occurrence of rain. 



The ova, I conclude, are deposited on the surface 

 of the mud, where they remain unhatched so long as 

 the pond continues dry. 



