Jan. 30, 1890J 



NATURE 



309 



faces and the incision bore such characteristic traces of meteoric 

 iron as to show that the mass was not the work of man. A 

 layer of oxide formed a thin covering of the iron ; it was 67 mm. 

 high, 67 mm. broad, and 47 mm. at its thickest part ; it was 

 found to be about as hard as steel, and besides carbon it con- 

 tained a small percentage of nickel. It resembled the meteoric 

 masses of St. Catherine in Brazil, and Braunau in Bohemia, 

 found in 1847. 



The evidence, however, is so strong that what we really obtain 

 now at the earth's surface forms but a very small portion of the 

 meteorites which enter the upper air, that it would not be 

 probable that in former ages of the earth's history, when the 

 atmosphere was denser than it is now, anything whatever would 

 be left by the time the surface was reached. 



J. Norman Lockyer. 



SCIENTIFIC SERIALS. 



American Journal of Science, January. — Measurement of the 

 Peruvian arc, by E. D. Preston. In this paper, which was 

 read before the American Association for the Advancement of 

 Science at Toronto, August 1889, the author reviews the whole 

 question of the relative lengths of the earth's axes, dealing in 

 detail with Bouguer's expedition to Peru in 1735, ^od arguing 

 that the amplitude of his Peruvian arc may be in error by many 

 seconds. Hence he contends that the geodetic science of to-day 

 demands the remeasurement of this arc. — Neutralization of 

 induction, by John Trowbridge and Samuel Sheldon. A system 

 of neutrah'zation for inductive disturbances is here described, 

 which might be adopted where it is impossible to employ entire 

 metallic circuits in which the earth plays no part. — Divergent 

 evolution and the Darwinian theory, by Rev. John T. Gulick. 

 The author discusses Darwin's apparently contradictory views 

 on the causes of natural selection on the one hand, and on the 

 other on the causes of diversity of natural selection. He con- 

 cludes that, though Darwin has not recognized segregation as a 

 necessary condition of divergence of species, he has indicated 

 one process (geographical or local separation under different 

 environments) by which segregation is produced in nature, 

 adding, however, that this is not the only cause of segregation 

 and consequent divergence. — The Devonian system of North 

 and South Devonshire, by H. S. Williams. During a recent 

 visit to England the author studied this system both on the spot 

 and- in the geological collections in London and elsewhere. He 

 dwells especially, (i) on the close resemblance of the English 

 Devonian species to those of the New York Devonian, though 

 mostly passing under different names, and (2) on the character 

 of the North and Souih Devonian rocks, which in appearance, 

 composition, and order are as different as two distinct systems 

 well can be. — The zinciferous clays of South- West Missouri, 

 and a theory as to the growth of the calamine of that section, 

 by W.- H. Seamon. Full analyses are given of the so-called 

 "tallow" and "joint" clays occurring associated and sometimes 

 intermixed in every calamine digging in South- West Missouri. 

 These analyses show a large percentage, often from 50 to 

 56, of zinc oxide, and it is inferred that at one time all 

 the massive calamine probably existed in "tallow clays" pre- 

 cipitated from solutions. — On the spectrum of f Ursas Majoris, 

 by Edward C. Pickering — Origin of normal faults, by T. 

 Mellard Reade. Some critical remarks are offered on Prof. 

 Le Conte's recent explanation of the origin of normal faults, 

 which is not new, and presents many insuperable difficul- 

 ties. — Papers were submitted by J. Dawson Hawkins, on a 

 specimen of minium from Leadville ; by W^illiam P. Blake, on 

 some minerals from Arizona ; by F. A. Genth, on a new oc- 

 currence of corundum in Patrick County, Virginia ; by Alfred 

 C. Lane, on the estimation of the optical angle of observations 

 in parallel light ; by L. G. Eakins, on a new stone meteorite 

 from Texas ; by Edward S. Dana, on the barium sulphate from 

 Perkin's Mill, Templeton, Province of Quebec ; and by O. C. 

 Marsh, on some new Dinosaurian reptiles recently discovered 

 in Wyoming, Colorado, and Dakota. 



SOCIETIES AND ACADEMIES. 



London. 



Royal Society, January 9.— "A Milk Dentition in Orycte- 

 ropus." By Oldfield Thomas, Natural History Museum, Com- 

 municated by Dr. A. Giinther, F.R.S. 



Of the few Mammalia in which no trace of a milk dentition 



has betn found, Orycteropus, the Aard-Vark, has always occupied 

 a prominent place, owing partly to the peculiar structure of its 

 prominent teeth, and partly to its very doubtful systematic 

 position. 



An opportunity has now fallen in my way of proving that it 

 has after all two sets of teeth, those of the first, or milk set, 

 being rudimentary, and probably quite functionless, but never- 

 theless so far developed as to be all completely calcified, and to 

 be for the most part readily distinguishable by form and position 

 from those of the second or permanent set. 



Among the collections in the Natural History Museum there 

 are two very young females of Orycteropns afer in spirit, pre- 

 sented by Sir Richard Owen, and it is in these that the milk 

 teeth now to be described occur. The larger of the two measures 

 18 inches in total length, and the smaller 14 inches. 



Each of these specimens has a complete, although rudi- 

 mentary, set of milk teeth, extending the whole length of the 

 maxillary bones above, and along a rather shorter portion of the 

 mandible below. None, however, are observable in the pre- 

 maxillse, or in the corresponding anterior part of the mandibles. 

 The teeth are all quite minute, and it is doubtful whether they 

 would ever have cut the gum. 



In the upper jaw there appear to be normally no less than 

 seven milk teeth. Of these the most posterior is by far the 

 largest, has a rudimentary crown, and two distinct roots, anterior 

 and posterior. The others are simple and styliform. 



In the lower jaw there are four milk teeth only, of which, 

 again, the most posterior is more or less molariform. 



As to the structure of the milk teeth, a horizontal section of 

 the last upper one, ground down in the dry state, presents 

 numerous large openings which are obviously the sockets into 

 which pulp-papilla; have extended, so that the milk teeth show 

 a commencement of the remarkable histological structure cha- 

 racteristic of the permanent teeth. 



But important as a knowledge of the presence of a milk denti- 

 tion in Orycteropus is, it does not at present render any easier 

 the difficult questions as to the phylogeny and systematic position 

 of that animal. Although called an Edendate, it has always, 

 been recognized as possessing many characters exceedingly 

 different from those of the typical American members of the 

 order. ^ It has in fact been placed with them rather on account- 

 of the inconvenience of forming a special order for its reception, 

 than because of its real relationship to them. Now, as they are 

 either altogether toothless or else homodont and monophyodont 

 (apart from the remarkable exception of Tatusia), it seems more 

 than ever incorrect to unite with them the solitary member of 

 the Tubulideittata, toothed, heterodont, and diphyodont, and' 

 differing from them in addition by its placentation, the anatomy 

 of its reproductive organs, the minute structure of its teeth, and; 

 the general characters of its skeleton. 



But if Orycteropus vs, not genetically a near relation of the 

 Edendates, we are wholly in the dark as to what other Mammals 

 it is allied to, and I think it would be premature to hazard a 

 guess on the subject. W^hether even it has any special connec- 

 tion with Manis is a point about which there is the greatest 

 doubt, and, unfortunately, we are as yet absolutely without any,- 

 palseontological knowledge of the extinct allies of either. 

 Macrotherium even, usually supposed from the structure of itS; 

 phalangeal bones to be related to Manis, has lately proved (see 

 Osborn, American Naturalist, vol. xxii. p. 728, 1882) to have- 

 the teeth and vertebrae of a Perissodactyle Ungulate, and one 

 could not dare to suggest that the ancestors of Manis or 

 Orycteropus were to be sought in that direction. Lastly, as the 

 numerous fossil American Edentates do not show the slightest 

 tendency to an approximation towards the Old World forms, we 

 are furnished with an additional reason for insisting on the 

 radical distinctness of the latter, whose phylogeny must therefore 

 remain for the present one of the many unsolved zoological 

 problems. 



Physical Society, January 17. — Prof. W. G. Adams, Vice- 

 President, in the chair. — Owing to the unavoidable absence of 

 Mr. F. B. Hawes, his paper on a carbon deposit in a Blake 

 telephone transmitter was postponed. — Dr, S. P. Thompson 

 made a communication on electric splashes, and illustrated his 

 subject by beautiful experiments on the production of Lichten- 

 berg's figures. The author has recently investigated these 

 phenomena as modified by varying the conditions under which 



* On this subject see especially Flower, ' ' On the Mutual Affinities of the 

 Anim.-ils composing the Order Edent.-\ta," Zool. Soc. Proc, 1882, p. 358*/ 

 seqq. 



