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The closure of an oyster upon one of the toes of a golden plover was recorded in the Field, in 1889,' and the taking of a cormorant with an oyster upon its bill was reported, in 1892, in the Daily News. Many other similar records, no doubt, might be found; but we must pass on to the consideration of facts which have a more direct bearing upon the subject in hand.

INSECTS.

From the number of observations which have been made, it seems that small fresh-water bivalves, such as Sphærium and Pisidium, frequently attach themselves to aquatic insects.

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Sphærium corneum upon the leg of a Dragon-fly-larva; taken at Twenty Pits, near Manchester, and now in the Manchester Museum.

The larva of a dragon-fly with a shell of Spharium corneum clinging to one of its legs was once caught at Twenty Pits, near Manchester, and the specimen preserved with the shell attached (Fig. 1) is 'Field," lxxiii. (1889), 308.

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now to be seen in the Manchester Museum, where it was deposited by Mr. Hardy. This occurrence, however, is not of much importance for us, for I am not aware that dragon-fly larvæ ever journey overland.

The clinging of bivalves to flying water-bugs and -beetles is of more interest. Five individuals, at least, of the water-scorpion (Nepa), a large flying bug, have been caught with shells attached. A specimen with a small Sphærium corneum on one of its legs, obtained in 1879 from Mere Mere, Cheshire, by Mr. J. Walken, is now exhibited in the Manchester Museum, where, also, is another specimen (preserved in spirit) having attached to it a much larger shell of the same species; two others, collected by Mr. Hardy in 1889, each carrying a shell of Pisidium fontinale upon a leg of the hind pair, are also possessed by the Museum. (Fig. 2.) A fifth

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Pisidium fontinale upon the leg of a water-scorpion (Nepa); now in the Manchester Museum,

instance has been observed by Mr. Standen, who caught a specimen with P. fontinale attached, in a pond near Birch Hall, Manchester, on 16th May, 1890.

A number of water-bugs (Notonecta) with "small

mollusks attached to their legs," were exhibited by Mr. Whitelegge at a meeting of the Linnean Society of New South Wales in 1885, and I hear from Mr. C. Hedley that in the vicinity of Sydney, Mr. Whitelegge has frequently noticed hemipterous insects, both Notonecta and Corixa, laden with bivalves: three specimens of Pisidium etheridgei have been seen attached to one insect, one on each fore-leg and one on the snout.

Quite a number of instances of the clinging of these molluscs to water-beetles can be given. As stated by Mr. Darwin in a letter published in "Nature" in 1882, a specimen of the "great water-beetle," Dytiscus marginalis, with a shell of Cyclas cornea [=Sphærium corneum] clinging to one of its legs, was caught by Mr. W. D. Crick, of Northampton, on 18th February of that year :

"The shell was 45 of an inch from end to end, 3 in depth, and weighed (as Mr. Crick informs me) 39 grams, or six grains. The valves clipped only the extremity of the tarsus for a length of 'I of an inch. Nevertheless, the shell did not drop off, on the beetle when caught shaking its leg violently. The specimen was brought home in a handkerchief, and placed after about three hours in water; and the shell remained attached from February 18th to 23rd, when it dropped off, being still alive, and so remained for about a fortnight while in my possession." "

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1 "Proc. Lin. Soc., N.S.W.," x. (1886), 760.

2 Darwin, "Nature," xxv. (1882), 529-30; and see also "Life and Letters,” iii. (1888), 252.

Other specimens of the same kind of water-beetle with Sphærium corneum attached have since been obtained: Mr. C. Oldham found one, with a shell of good size firmly clasping the extremity of one of the front legs, in a pond at Woodford, Essex, in September, 1886; and I had the good fortune to catch a specimen

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Spharium corneum upon the leg of a water-beetle (Dytiscus); taken at West Barkwith, Lincolnshire, and now in the Manchester Museum.

with a shell upon the right front leg in a pond at West Barkwith, Lincolnshire, in August, 1888 (Fig. 3).' Mr. W. H. Heathcote found another specimen with a shell similarly attached at Farington, Lancashire, in 1889; and a further case, in which a small shell was attached to one of the hind legs of the beetle, was observed by Mr. Standen, in June, 1890, in a pond at Birch, near Manchester.

Some large water-beetles, kept by Mr. Norgate in an aquarium, Mr. Darwin states, frequently had one foot caught by a small by a small fresh-water fresh-water bivalve (S.

corneum ?) 2

1 "Journ. of Conch.," vi. (1888), 363; "Proc. Ent. Soc., Lond," 1888, p. xxxv.

2 "Nature," xxv. (1882), 529-30.

A specimen of Dytiscus marginalis with a shell of Sphærium lacustre clinging to one of the front legs was caught by Mr. Standen, in a pond at Gorton, in 1890. The shell had been slightly broken, probably from having been dashed against some object by the insect, but, being still alive, it held on tightly. A beetle belonging to the allied genus Acilius with a shell of Pisidium fontinale on one of the legs of the second pair has been presented to the Manchester Museum by Mr. Hardy,' and I hear from Sydney that two water-beetles with Pisidia attached were obtained by Mr. Whitelegge (now of the Australian Museum) when collecting, years ago, in Lancashire; in one of the cases two shells were clinging to the same insect, one on each side.

Two or three instances of the clinging of bivalves to the antennæ of water-beetles have been observed, and Mr. A. J. Jenkins tells me that in a large bell-glass, which he used as a sort of aquarium, a Pisidium on one occasion fastened its valves tightly upon one of the maxillipedes of a shrimp.

Before coming to any conclusion as to whether waterbeetles, -bugs, etc., have much affected the ranges of bivalve-molluscs and have helped in any perceptible degree to stock newly formed and isolated ponds with

This and the other specimens here stated to have been presented to the Manchester Museum were obligingly sent to me in London for examination; two of them, I regret to say, were damaged in the post.

? A case of this kind once came under the observation of Mr. Hardy; another is recorded in "Science Gossip," 1873, p. 190, and see also"Nature," xxv. (1882), 529-30.

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