476 



NATURE 



\Oct. 4, 1877 



The Oinithorhyiichus being an aquatic animal does not possess 

 a pouch at any time. With respect to the New Guinea species 

 of Echidna, tlie' question wliether the Tachyglossiis lawsei and T. 

 liriiijnii are distinct species can now be decidt d, as I observe that 

 examples of both sexes of T. brnijnii have been obtained in the 

 mountains on the north coast of New Guinea at an elevation of 

 about 3,500 feet. That a new and somewhat analogous species 

 of Tachyglossus may yet be discovered in Northern Australia I 

 consider very probable. George Bennett 



September 29 



P.S. — By letters from Sydney dated August 4 no intelligence 

 lias been received from Sig. D'Albeitis since his departure for 

 the Fly River in May last. 



Are there no Boulders in Orkney and Shetland? 



In your impression of the 13th inst. (p. 418), there is an 

 interesting letter from Mr. Laing, M.P., stating that there are 

 no boulders in Orkney or .Shetland. He says that having " an 

 intimate personal acquaintance with these islands, which are my 

 native county, and almost every yard of whose surface and shores I 

 have explored with rod and gun," . . . "1 can assert positively 

 that I never saw (in them) a lioulder or perched block, or the 

 trace of any till, or boulder clay, kame, eskar, raised beach, or 

 other form of glacial or marine action." 



Mr. Laing's object in drawing the attention of geologists to 

 these facts is, that "if true, they seem to afford a crucial test of 

 the truth or falsehood of some of the most important theories of 

 modern geology." 



Mr. Laing observes that in Orkney therfi could be no boulders, 

 &c., because " there were no glaciers, there being no great local 

 mass of mountains to produce them." 



As regards .Shetland, Mr. Laing says he cannot speak with the 

 same confidence. "Still, having travelled over a great part of 

 the principal islands, I can assert that I have never seen in them 

 either, any tr.ices of glacial action." 



Mr. Laing having invited information on this subject. Prof. 

 Geikie has published an article in the same number of your 

 paper (p. 414), controverting Mr. Laing's statements, and main- 

 taining that the facts ascertained by hiii and his colleagues in 

 the Scotch Geological Survey establish that these islands form 

 "no exception to the general glaciated condition of Scotland." 



In corroboration, so far, of the Professor's statement, that 

 there are in Orkney and Shetland "many transported blocks of 

 gneiss, 'schist, and other rocks foreign to the immediate locality" 

 of the blocks, I need only refer to the following list of boulders 

 reported to the Edinburgh Royal Society Boulder Committee. 

 In OrIvNEY. 



Eday Is!and. — Conglomerate B. 12 X 7 X ij feet, = about 

 8 tons weight. Situated near top of a hill 250 feet above sea. 

 No conglomerate rock in Eday, but there is in Stronsay Islind. 



Frith and Stennis. — White pebbles of freestone on the hills. 

 But there are no white freestone rocks in this island. It is all 

 old red. 



Sandny. — Gneiss B. 7 X 6 X 25 feet = about 14 tons. No 

 gneiss rocks on this island. Nearest island with gneiss rocks 

 is Stromness, 30 miles distant, and in Shetland, still more 

 distant. 



IValls. — Lydian stone B. 9 X 7 X 6 feet = about twenty- 

 eight tons. Sandstone is the prevailing rock. 



Stroiiitwss Island. — Two granite boulders lying on red sand- 

 stone rocks — distant, one a quarter of a mile, the other one mile 

 from granite hills. 



In Shetland. 



Bressay. — A number of boulders here, of a rock foreign to the 

 island. One of them is 10 x 7 x 4 feet. Supposed to have 

 been transported from Norway. 



Housay. — On a cUff 200 fett above the sea,' rounded blocks 

 resting on knolls of polished rock. 



Ncay. — Large perched blocks, some many tons in weight. 



Sujnburgh Iliad. — Conglomerate B. lying on sandstone rock. 



Wheie can it be supposed that these boulders come from ? 



Prof Geikie thinks there were glaciers, at all events, in one 

 of the islands, viz., Hay, and even "separate glaciers " in all the 

 valleys of that hill, whose top is only 1,550 feet above the sea. 

 I feel great difficulty in subscribing to that opinion ; I rather 

 agree with Mr. Laing, that there could be no glaciers, for want 

 of a sufficient "mass of mountain region to produce them." 

 Even if in Hoy glaciers could have been formed on a hill the 

 highest peak of which is only 1,550 feet above the adjoining sea, 

 what is to be said of those boulders which are on islands where 



the hills do not exceed 500 or 200 feet, and in which there are 

 no rocks of the same nature as the boulders? 



Piof Geikie refers to the rock striuions in Orkney and Shet- 

 land (which Mr. Laing seems not to have discovered) as additional 

 proofs of glacial action. If these striations had been caused by 

 glaciers, the direction of the stricc would vary with the direction 

 of the different valleys in which the glaciers moved. But this is 

 found not to be the case. Prof. Geikie says that both in Orkney 

 and in Shetland the movement of the ice h.as been on the " whole 

 along a north-west and south-east line." He refers to reports 

 by his colleagues, Mr. Peach and Mr. Home, in corroboration 

 of his statements. 



la looking into Mr. Peach's report, I find that he specifies the 

 stride on the rocks of Shetland as running in vat-ious directions. 

 In Unst, the most northern island, he says "the destroying force 

 (the nature of which force, however, he avoids indicating) coming 

 against a hill (cilled the ' Miich/i Hca^,' $00 feci high) on its 

 north-west fiank, had been partially turned by the hill into a 

 valley (which he names) and made to produce the well-known 

 phenomenon of ' crag and tail ' " — the cr.ag or bared rock being 

 on the north side of the lull. 



Mr. Home in his paper also describes the striae in Shetland as 

 running in various different directions. Some of the strife on the 

 rocks, and the boulders on the surface, indicated, as he thought, 

 ice action from east to west. "In addition to these, however, 

 others (he sa\s) were found, which could not have been produced 

 by ice-shedding in the ordinary way. These cross the island, 

 regardless of its physical features, and are often at right angles to 

 the newer set." 



These facts, I venture to submit, may be explained by suppos- 

 ing that the .Shetland and Orkney Islands, when still under the 

 ocean, were subjected to the action of Arctic currents loaded 

 with icebergs and shore ice. We know that in the Arctic regions 

 now, fragments of rocks are by these means carried about in 

 various directions, and dropped on the sea-bottom ; whilst the 

 rocks at the sea bottom are ground down, polished and striated 

 by the hard stones and gravel pushed forward by icebergs. 

 The existence of Arctic currents from north-western points has 

 indeed been already well established by a study of the boulders 

 and striated rocks found along the west coasts of Caithness, Ross, 

 Argyll, and the islands of Lewis, Harris, and Uist. 



i'he inference of Mr. Peach from what he saw near Lerwick 

 was, that there "the direction the drift came from is evidently 

 northerly." "The destroying force" to which Mr. Peach refers 

 as having swept across the i.^jand of Unst baring a hill up to a 

 height of 500 feet on its north-west flank, could have been no 

 other than an Arctic current loaded with ice. 



These facts establish points of the highest geological interest. 

 They indicate a submersion of the northern parts of Europe under 

 the ocean to the extent of many hundred feet, and the non-exist- 

 ence of any gulf-stream flowing through the North Atlantic. 

 The Isthmus of Panama requires to be depressed only 350 feet, 

 to allow that stream to flow into the P.icific. 



The separate question of " I\aised beaches" mooieA by Mr. 

 Laing and discussed by Prof. Geikie, I do not enter on. Both 

 of these authorities agree that there are no raised beaches in 

 Shetland and Orkney. It is indeed very curious that such should 

 be the case, considering that they exist along the Caithness coast, 

 and in every other part of the kingdom, including Ireland. I 

 may, however, notice that Mr. Peach in hisReport on Shetland 

 speaks of a " raised beach " as having been seen by him there. 



Milne Graden, Coldstream, N.B. David Milne Home 



Fertilisation of Flowers by Birds 

 Among the " Biological Notes " in Nature, vol. xv. p. 

 416, there is one referring to the agency of birds in effecting the 

 fertilisation of flowers. A Itw weeks before reading this note I 

 was induced to suspect that many flowers might be dependent 

 wholly or in part on the visits of small birds for their effectual 

 fertilisation by observing that a very considerable number of 

 birds shot at that time had the plumes of the forehead and the 

 lores thickly dusted with pollen. This fact was noticed in seveial 

 species of Z);ciy/«(r and jVec'ariniinie, i:i the Zoriculi, and even 

 in a glossy starling {Calornis panaymsis), which latter is mainly 

 a frugivorous bird. Both the sun-birds and flower-peckers are 

 fruit-ieeders to a certain extent ; but they also prey on ndnu.e 

 insects, in search of which (and possibly of the nectar sometimes) 

 they diligently probe the corollas of numerous flowers, and on 

 withdrawing their heads a portion of the pollen remains in many 

 instances adhering to the plumage bordering the bill, and is 

 carried away and introduced into the next blossom visited. 



