Janiabv 1, 1901.] 



KNOWLEDGE 



19 



Tht Bird-t of Yorkshire. — Xl>e Uouornrv Secretary of tlio York- 

 shire Xaturalists' Union annoiiuees tliat Mr. T II. Nelson lias under- 

 taken to continue and complole .Mr. W. Hagle Clarke's work on the 

 "Birds of Yorkshiiv," whiih lia." been partly published in the 

 Transactions of the Yorkshire Naturalists' Union, and the continua- 

 tion of which w^»s interrupted by Mr. Clarke leaving Yorkshire to 

 settle in Edinburgh, l^onsidering the leiiiith of tin\e that Invs elapsed, 

 and the number of records and observations of Y'ortishire birds which 

 hive accumulate.! sinoe Mr. Clarke wrote his last instalment of this 

 work, we think it \inwise to continue the yniblication. Good as we 

 know Mr. Clarke's work to be, such revision is required in bringing it 

 up to date that nothing short of rewriting would be satisfnetovy. 

 Moreorer, Messrs. Oxley Graham and James Packhousc have long 

 been euga;jed on a work on the birds of Yorkshire, tlie manuscript of 

 wliich we miderstaud is now nearly complete. 



Pectoral Sandpiper at Aldehurcjh (Zoologist, November, 1900, 

 p. 521). Mr. E. C. Arnold records that he shot a specimen of Trini/n 

 maciilala on September 13th last at Aldehurgh, Suffolk. This bird 

 has occurred in England more frequently than any other .Vmerican 

 wader, and has already been recorded four times from Suffolk. 



All contributions to tJie column, either in the way of notes 

 or photographs, should he foruardcd to Harr'T F. Witherby, 

 at 1, Eliot Place, Blackheath, Kent. 



THE INSECTS OF THE SEA. 



B_v Geo. H. Cakpenteh, b.sc.(lond.j, Axsislanl in the 

 Miii>etii)i of Science and Art, Dublin. 



INTRODUCTORY. 



Marine insects have been somewhat neglected both by 

 entomologists and by students of the " common objects of 

 the sea^shore." An ai-dent insect-hunter will quickly fill 

 his boxes, as he wanders over the hillside, or sweeps 

 along the thick undergrowth of the woodland, while hours 

 of work along the tidal margin may yield him but a 

 few obscure flies and beetles. And the nattu-alist who 

 finds especial delight in the rock-pool or the wave-swopt 

 beach, is usually so engrossed with his shells or his 

 zoophytes that he does not notice the insects lurking 

 beneath the stones or crawling among the seaweed. 

 Hence so keen a naturalist as the late P. H. Gosso* 

 told his readers forty-five years ago that "of the hun- 

 dreds of thousands of insects known to exist but (ico 

 live in the sea." Even at that date the statement was 

 much under the mark. Leach, Guerin, and Haliday 

 had years before detected and described many of the 

 shore-haunting insects which will be mentioned at length 

 hereafter; while as early as 1822, Eschsholtz had made 

 known the wonderful bugs of the genus Halobates, the 

 only insects whose whole life is spent on the open sea. 

 In 1871, A. S. Packardt mentioned some dozen marine 

 species from the Atlantic and Pacific coasts of North 

 America. References to marine insects in the works of 

 recent writ-ers — Moniez]; and Miall§ for example — show 

 that some scores of kinds probably occur on our own 

 coasts, most of the important orders being represented. 

 And it is likely that the marine insects of the whole 

 world will be found to number some hundreds of species. 

 Still the insects of the sea seem but an insignificant 

 group when we compare them with the well-nigh coiuit- 

 less kinds of insects that inhabit the air and the laiul, 

 two millions according to the lowest recent estimate, 



* "Manual of Marine Zoology for the British Isles," Part 1. 

 p. 178. London, 1855. 



t " On Insects inhabiting Salt Water." Amer. Journ. Sci., 1K71 ; 

 Ann. Mag. Sat. Bist. (1), VII., pp. 230-210. 



X " Acariens et Insectes marins des C6tes du Buulonnais." ifer. 

 Biol. Nord, France, II., 1889-90. 



§ "Ihe Natural History of Aquatic Insects,'' London, 1895, 

 ch. XII. 



and ten millions if wc may accept the opinion of .90 

 careful a naturalist as the late C. \ . Riley. Hundreds 

 only as compared with millions! it nright easily be 

 thought that maj'ine insects ai'e unworthy of the 

 natiu'alists attention. Yet their poverty in numbers 

 is really a sign of the value of the study; creatures so 

 few in comparison with their class as a whole must have 

 something exceptional about them, and their form and 

 life-history must yield I'esulta of high interest to the 

 patient enquirer. 



Insects are pre-eminently creatures of the air and 

 the land. The power of flight possessed by most insects, 

 the wonderful system of branching tubes found in almost 

 all — carrying air to all parts of the body sO' that oxy- 

 genation of the blood goes on everywhere^ — mark them 

 out as essentially a class of air-breathing animals. It 

 is well known that many insects pass the earlier stages 

 of their life-history in streaiiis aJid ponds, but com- 

 paratively few of the grubs have acquired the power 

 of breathing the air dissolved in water. Most a<juatic 

 lai"va, and all the insects which live in water when 

 adult, have to com© into touch with the upper air when 

 they want to breathe. Prof. Miall's fascinating work 

 on aquatic insects, to which reference has already been 

 made, is largely occupied with descriptions of the won- 

 derful adaptations whereby a supply of fresh air is 

 sccui'ed to these dwellers in the water. Since insects, 

 then, are so characteristically children of the air it is 

 of special interest to find that some have established 

 themselves close to, in, or on tlio waters of the sea. 

 The immense number of difl^ercnt kinds of insects must 

 make the struggle for life among them exceptionally 

 severe, and the existence of marine insects is a striking 

 proof of the hardship of the struggle. They have been 

 driven to adapt themselves to life in salt water, just as 

 thousands of the teeming human population of China 

 have been driven to live in house-boats and junks. 



The insect-fauna of the land and the freshwaters merges 

 gradually into that of the sea. Many genera of aquatic 

 insects have species which live in brackish water. There 

 are many kinds of beetles, flies, and moths, rarely or never 

 found elsewhere than on coast sand-dunes. These, how- 

 ever, live high and dry, and may be fairly regarded 

 as terrestrial species. Nearer the water's edge, where the 

 blown-sand passes into the beach, a row of blackened 

 seaweed marks the limit of the high spring tides. In 

 this a number of beetles may often be found ; over it 

 hover flies whose grubs ai-e feeding in the decomposing 

 mass below, and they must be able to bear at least 

 "occasional immersion. Right down by the water's edge, 

 along the margin of the i-ock-pools, lurking in the sea^ 

 weed covered twice daily by the waves, skimn\ing over 

 the surface-film, or swimming through the clear, calm 

 water when the tide is out, the true marine insects must 

 bo sought for and studied. Still more daring invaders 

 of the sea may be observed by the sailor-naturalist in 

 tropical climes. He will find some relations of our 

 common pond-skaters, skimming over the waters of 

 estuaries or harbours whore his ship lies becalmed, 

 and he will meet with others on the open ocean hundreds 

 of miles from Uind. 



Otu' survey of the insects of the sea will host be taken 

 order by order. The representative of the most primi- 

 tive of the orders — the Bristle-tails (Thysanura) — may 

 appropriately come first; though it lives close to the 

 water's edge, it seems rarely or never to be covered by 

 the tide. 



BRISTLE-TAILS. 



The marine member of the order Thysanura is the 



