We will now pass on to the Coleoptera, or beetles, an order which has been of late years energetically collected and carefully studied by British entomologists.
List of the Species and Varieties of Beetles which, so far as at present known, are confined to the British Islands. Those added since the first edition are marked with an asterisk.
Carabidæ.
1. *Bembidium saxatile, var. vectensis (Fowler). Isle of Wight.
2. Dromius vectensis (Rye). Common in the Isle of Wight, also in Kent, and at Weymouth and Seaton. Closely allied to D. sigma.
3. Harpalus latus, var. metallescens (Rye). Unique, but very marked! South coast. "Perhaps a sport or a hybrid" (Fowler).
4. Acupalpus derelictus (Dawson). Unique! North Kent. Canon Fowler thinks it may be a variety of A. dorsalis.
Dyticidæ.
5. *Acilius sulcatus, var. scoticus (Curtis). Scotland. A melanic variety.
Helophoridæ.
6. Ochthebius poweri (Rye). Very marked. S. coast. A few specimens only.
7. *O. æneus (Steph).
Brachyelytra.
8. Ocyusa hibernica (Rye). Ireland, mountain tops, and at Braemar.
9. *Oxypoda tarda (Sharp).
10. ,, pectita (Sharp). Scotland.
11. ,, verecunda (Sharp). Scotland, also London districts.
12. Homalota diversa (Sharp).
13. ,, fulvipennis (Rye).
14. ,, oblongiuscula (Sharp). Scotland, also England and Ireland.
15. ,, princeps (Sharp). A coast insect.
16. ,, curtipennis (Sharp). Scotland and near Birmingham.
17. H. levana, var. setigera (Sharp).
18. Stenus oscillator (Rye). Unique! South coast. May be a hybrid.
19. Trogophlæus spinicollis (Rye). Mersey estuary, unique! Most distinguishable, nothing like it in Europe. Perhaps imported from another continent.
20. Eudectus whitei (Sharp). Scotch hills. A variety of E. Giraudi of Germany (the only European species) fide Kraatz (Sharp).
21. Homalium rugulipenne (Rye). Exceedingly marked form. Northern and western coasts; rare.
22. *Mycetoporus monticola (Fowler). Cheviots and Inverness-shire.
Scydmænidæ.
23. *Scydmænus poweri (Fowler) S. England. A recent discovery.
24. *S. planifrons (Fowler). ,, ,,
Pselaphidæ.
25. Bryaxis cotus (De Sauley). Scotland.
26. Bythinus glabratus (Rye). Sussex coast; also Isle of Wight; a few specimens; very distinguishable; myrmecophilous (lives in ants' nests).
Trichopterygidæ.
27. Ptinella maria (Matthews) Derbyshire.
28. Trichopteryx saræ ( ,, ) Notts.
29. ,, poweri ( ,, ) Oxon.
30. ,, edithia ( ,, ) Kent.
31. ,, *angusta ( ,, ) Leicestershire.
32. ,, kirbii ( ,, ) Norfolk.
33. ,, fratercula ( ,, )
34. ,, waterhousii ( ,, )
35. ,, championis ( ,, ) Wicken Fen.
36. ,, jansoni ( ,, ) Leicestershire.
37. ,, suffocata (Haliday). Ireland, Co. Cork.
38. ,, carbonaria (Matthews). Notts.
39. Ptilium halidayi (Matthews). Sherwood Forest.
40. ,, caledonicum (Sharp). Scotland; very marked form.
41. ,, insigne (Matthews). London district.
42. *Orthoperus mundus (Matthews). Oxfordshire.
43. *O. punctulatus (Matthews). Lincolnshire.
Anisotomidæ.
44. Agathidium rhinoceros (Sharp). Old fir-woods in Perthshire; local, many specimens; a very marked species.
45. Anisotoma similata (Rye). South of England. Two specimens.
46. ,, lunicollis (Rye). North-east and South of England, a very marked form; several specimens.
Phalacridæ.
47. Phalacrus brisouti (Rye). South of England. Rare. "Perhaps a small form of P. coruscus" (Fowler).
Cryptophagidæ.
48. Atomaria divisa (Rye). Unique! South of England.
Lathridiidæ.
49. Melanopthalma transversalis, var. wollastoni (Waterhouse). South coast, and Lincolnshire.
Byrrhidæ.
50. Syncalypta hirsuta (Sharp). South of England, local. "Closely allied to S. setigera" (Fowler).
Mordellidæ.
51. *Anaspis septentrionalis. Scotland (1891). (Champion.)
52. * ,, garneysi (Fowler). London District. (1890.)
Telephoridæ.
53. Telephorus darwinianus (Sharp). Scotland, sea-coast. A stunted form of abnormal habits. Perhaps a variety of T. lituratus.
Cyphonidæ.
54. Cyphon punctipennis (Sharp). Scotland.
Anthicidæ.
55. Anthicus salinus (Crotch). South coast.
56. ,, scoticus (Rye). Loch Leven; very distinct; many specimens.
Cioidæ.
57. *Cis bilamellatus (Wood). West Wickham, Kent. "Perhaps imported. Has the appearance of an exotic Cis" (Fowler).
Tomicidæ.
58. *Pityopthorus lichtensteinii, var. scoticus (Blandford). Scotland.
Curculionidæ.
59. Ceuthorhynchus contractus, var. pallipes (Crotch). Lundy Island; several specimens. A curious variety only known from this island.
60. Liosomus troglodytes (Rye). A very queer form. Two or three specimens. South of England.
61. *Orcheites ilicis, var. nigripes (Fowler). London District. (1890.)
62. Apion ryei (Blackburn). Shetland Islands. Several specimens. Perhaps a var. of A. fagi.
Chrysomelidæ.
63. Chrysomela staphylea, var. sharpi (Fowler). Solway district.
Halticidæ.
64. Longitarsus agilis (Rye). South of England; many specimens.
65. ,, distinguenda (Rye). South of England; many specimens.
66. Psylliodes luridipennis (Kutschera). Lundy Island. A very curious form, not uncommon in this small island, to which it appears to be confined. "An extreme and local variety of P. chrysocephala" (Fowler).
Coccinellidæ.
67. Scymnus lividus (Bold). Northumberland. A doubtful species.
Of the sixty-seven species and varieties of beetles in the preceding list, a considerable number no doubt owe their presence there to the fact that they have not yet been discovered or recognised on the continent. This is almost certainly the case with many of those which have been separated from other species by very minute and obscure characters, and especially with the excessively minute Trichopterygidæ described by Mr. Matthews. There are others, however, to which this mode of getting rid of them will not apply, as they are so marked as to be at once recognised by any competent entomologist, and often so plentiful that they can be easily obtained when searched for. The peculiar species of Apion in the Shetland Islands is interesting, and may be connected with the very peculiar climatal conditions there prevailing, which have led in some cases to a change of habits, so that a species of weevil (Otiorhynchus maurus) always found on mountain sides in Scotland here occurs on the sea-shore. Still more curious is the occurrence of two distinct forms (a species and a well-marked variety) on the small granitic Lundy Island in the Bristol Channel. This island is about three miles long and twelve from the coast of Devonshire, consisting mainly of granite with a little of the Devonian formation, and the presence here of peculiar insects can only be due to isolation with special conditions, and immunity from enemies or competing forms. When we consider the similar islands off
the coast of Scotland and Ireland, with the Isle of Man and the Scilly Islands, none of which have been yet thoroughly explored for beetles, it is probable that many similar examples of peculiar isolated forms remain to be discovered.
Looking, then, at what seem to me the probabilities of the case from the standpoint of evolution and natural selection, and giving due weight to the facts of local distribution as they are actually presented to us, I am forced to differ from the opinion held by our best entomological authorities, and to believe that some at least, perhaps many, of the species which, in the present state of our knowledge, appear to be peculiar to our islands, are, not only apparently, but really, so peculiar.
I am indebted to Mr. Robert McLachlan for the following information on certain Trichopterous Neuroptera (or caddis-flies) which appear to be confined to our islands. The peculiar aquatic habits of the larvæ of these insects, some living in ponds or rivers, others in lakes, and others again only in clear mountain streams, render it not improbable that some of them should have become isolated and preserved in our islands, or that they should be modified owing to such isolation.
Trichoptera peculiar to the British Isles.
1. Philopotamus insularis. (? A variety of P. montanus.)—This can hardly be termed a British species or variety, because, so far as at present known, it is peculiar to the Island of Guernsey. It agrees structurally with P. montanus, a species found both in Britain and on the continent, but it differs in its strikingly yellow colour, and less pronounced markings. All the specimens from Guernsey are alike, and resident entomologists assured Mr. McLachlan that no other kind is known. Strange to say, some examples from Jersey differ considerably, resembling the common European and British form. Even should this peculiar variety be at some future time found on the continent it would still be a remarkable fact that the form of insect inhabiting two small islands only twenty miles apart should constantly differ; but as Jersey is between Guernsey and the coast, it seems just possible that the more insular conditions, and perhaps some peculiarity of the soil and water in the former island, have really led to the production or preservation of a well-marked variety of insect. In the first edition of this work two other species were named as then, peculiar to Britain—Setodes argentipunctella and Rhyacophila munda, but both have now been taken on the continent.
2. Mesophylax impunctatus, var. zetlandicus.—A variety of a South and Central European species, one specimen of which has been found in Dumfriesshire. The variety is distinguished by its small size and dark colour.