300 



NATURE 



\_yan. 24, I 



stature, of the differences between the two foregoing 

 (which indicate the total length of the lower limbs), and 

 of the span. Anthropologists seem to have little idea of 

 the wide fields of inquiry open to them as soon as they 

 are prepared to deal with individual variety and cease to 

 narrow their view to the consideration of the average. 



Enough has now been said to justify the claims with 

 which 1 started, and which take this final form. First, 

 wherever it is likely to be of use, that, in series of which 

 the M is calculated, the measures at a certain number 

 of selected grades should also be calculated and given, 

 sufficient to enable the rest of the series to be found with 

 adequate accuracy by interpolation. Secondly, that the 

 value of Q should always be given, as well as that for M, 

 for two reasons. The one is, that they suffice between 

 them to give an approximate determination of the whole 

 series, more closely approximate as the series is more 

 closely of the normal type ; and, secondly, because O is 

 an essential datum before any application can be made 

 of the law of frequency of error. The properties of this 

 law are, as we have seen, largely available in anthropo- 

 logical inquiry. They enable us to define the trustworthi- 

 ness of our results, and to deal with such interesting 

 problems as those of correlation and family resemblance, 

 which cannot be solved without its help. 



Table of ordinates to normal curve of distrilmtion, in which 

 the unit = the probable error, and the grades, which are the 

 abscissce, run from 0° to 100". 



This table is an inverse rendering of the values derived by interpolation from 

 the ordinary table of the probability integral, but its unit is changed from that 

 of the modulus to that of the probable error, Q. and the (centesimal) grades 

 are reckoned from o'' to loa'. In the usual way of reckoning, the soth 

 grade should have been reckoned as 0°, and the deviations should have run 

 on the one side down to - 50°, and on the other up to \- 50°. 



Referring to what was said some way back, that if 30 per cent, fail to pull 

 60 pounds, then 60 pounds must be taken as the measure corresponding to 

 grade 30°, the reason is as follows. 'J he 30th grade separates the man 

 who ranks 30th in a class of 100 men from his neighbour who ranks 31st. It 

 does so for the same reason that grade 1° separates the man who ranks ist 

 from the man who ranks 2nd. Now, the 30th man failed in the test, and 

 the 31st succeeded. Therefore the grade corresponding to bare success 

 lies between them, and is the same as grade 30". 



SUPPOSED FOSSILS FROM THE SOUTHERN 



HIGHLANDS. 

 r\^ Monday, the 14th instant, the Royal Society of 

 ^-^ Edinburgh held a special meeting for the purpose 

 of hearing a discussion on the crystalline rocks of the 

 Scottish Highlands. The subject was brought forward 

 by the Duke of Argyll, who had found in the quartzite 

 beds which cross Loch Fyne near Inveraray certain 

 markings which he believed to be of organic origin. His 

 attention was first called to some ferruginous stalk- 

 like incrustations on the surfaces of fragments of quartzite, 

 his impression being that these markings were the remains 

 of plants, and were embedded in the rock. The import- 

 ance of the discovery of organic remains in any of the 

 rocks that form the Central and Southern Highlands of 

 Scotland will at once be recognized by geologists. Since 

 the recent work of the Geological Survey in Sutherland 

 and Ross, and the demonstration thereby afforded that 

 the apparent upward succession on which Murchison 

 relied, from the base of the lowest quartzite up into the 



upper or eastern or younger gneisses, is deceptive, there 

 has been, perhaps, a tendency to assume that the extra- 

 ordinarily complicated structure that supervenes to the 

 east of the quartzites and limestones of Sutherland 

 extends across the whole of the rest of the Highlands, 

 and that the crystalline schists of these regions are made 

 up of all kinds of crushed and sheared igneous or sedi- 

 mentary masses, out of which it may be impossible to 

 make anything like intelligible order. But those ob- 

 servers who have themselves examined the schists of the 

 central and southern counties of the Highlands are 

 tolerably confident that such assumptions have no warrant 

 in the actual structure of the ground. On the contrary, 

 they regard the greater proportion of the schistose and 

 altered rocks of these districts as unquestionably of 

 sedimentary origin. They feel persuaded that sooner or 

 later they will be found to yield fossils, and that any day 

 may bring to light a series of corals, shells, graptolites, 

 or trilobites, which will furnish a palasontological basis 

 for settling the geological age of the rocks, and placing 

 them in their true position with regard to the Palaeozoic 

 formations of the rest of the country. 



The announcement that the Duke of Argyll had found 

 what seemed to be organic remains in the Inveraray 

 quartzites awakened accordingly much interest among 

 geologists. His Grace soon discovered, however, that 

 what he had at first believed to be fossils were only 

 external markings due to the precipitation of hydrous 

 peroxide of iron round the decaying stems of mosses, 

 heaths, or other plants. These markings occurred in- 

 differently on pieces of quartzite, mica-schist, gneiss, &c., 

 and in no instance were found within the stone, but 

 always on the surface. But in turning over the exposed 

 blocks of quartzite the Duke found numerous ferruginous 

 markings which undoubtedly occurred all through the in- 

 terior of the rock. After quarrying away portions of 

 the solid rock, collecting a large series of specimens, 

 and comparing them with others obtained from 

 the quartzite of Sutherland, he deemed himself in a 

 position to announce the probably organic nature of 

 these markings ; and the paper which he communicated 

 last week to the Royal Society of Edinburgh gave 

 the results of his inquiries. The bodies which he regards 

 as fossils are compared by him to the "annelid burrows" 

 which form so prominent a feature in the quartzites of 

 Sutherland and Ross. He recognizes in the Inveraray 

 rock similar ovate sections, the position and form of each 

 tube being marked by a ferruginous ring, which is well 

 defined along its inner margin, but fades outward into a 

 general discoloration of the stone. He points out that 

 in the Inveraray rock, as in that of the North-West High- 

 lands, there is a general tendency of these ovate bodies to 

 he in one prevalent direction ; and though he admits that 

 the rocks have been considerably disturbed and crushed, 

 he cannot trace among them any evidence of such 

 stupendous movements as have been described from 

 Sutherland. Accordingly he is disposed to look upon the 

 parallelism of the stripes into which he thinks the original 

 tubes have been flattened as evidence of the direction in 

 which the worms burrowed through the still soft sand. 



Perhaps the most original and valuable part of the 

 Duke's paper was the account which he gave of his own 

 experiments on the habits of the common lob-worms of 

 our present shores. He had watched the operations of 

 these creatures on the beach of dark silt at Inveraray ; 

 had cut out- portions of the silt with the burrows and 

 mounds intact, and had these removed to his own 

 drawing-room to enable him to watch them more atten- 

 tively. He had likewise injected plaster of Paris into the 

 vertical or winding passages made by the worms in the 

 silt, and had thereby obt-ained casts of the interior of 

 these tunnels. He exhibited a very interesting and valuable 

 collection of specimens illustrating these researches. 

 Mr. Ceikie, the Director-General of the Geological 



