368 



NA TURE 



\^March ii, 1875 



breaking. This, however, is only the case with new ice, as after 

 a short time the salt crystallises out of the ice, anil the surface 

 covers itself with a snowy layer of salt, sometimes reaching 

 two inches of thickness. Even in the most intense cold this layer 

 retains so much moisture that it makes the impression of a thaw ; 

 only little by little, evaporation and drizzling snow do their work, 

 and the ice itself becomes brittle. 



In this way almost all the salt, which was frozen in, crystal- 

 lises out, and is washed off and back into the sea by the melted 

 water in the next summer. The melted water at the end of the 

 summer is therefore almost free from salt, and has a specific 

 gravity of I '005. It is evident that a smooth plane of ice, as is 

 found on sweet water, is a very rare occurrence in Arctic regions. 



The finest and most interesling phenomenon, the only charge 

 in the long night of winter, is the Aurora Borealis ; no pen can de- 

 scribe the magnificence of this phenomenon in its greatest intensity. 

 In February 1874 Lieut. Weyprecht saw an aurora, which ran 

 beyond the zenith from east to west like an immense stream of 

 fire, and constantly showed intense prismatic colours running 

 like flames, and as quick as lightning, from one side of the 

 horizon to the other. At the same time flashes of fire came 

 from the southern horizon and reached to the magnetic pole ; it 

 was the most stupendous natural display of fireworks he had ever 

 been able to imagine. With regard to the intensity of the 

 aurora, Lieut. Weyprecht says he can prove by data that il 

 differs, independently of the geographical latitude, in the different 

 parts of the Arctic zone, and that the district he visited was a 

 maximal district ; whf n the sky was clear, traces of auroras could 

 be uninterruptedly observed ; in the second winter be even kept 

 an "aurora journal," which, however, gave only few positive 

 results, and was left behind in the ship. The phenomenon is 

 past all description and classification, changing constantly and 

 showing new forms at eveiy moment. Lieut. Weyprecht was 

 never able to describe the origin of an aurora ; the phenomenon 

 is there, and it is impossible to say whence it came. 



Only in a very general way three forms of aurorse can be dis- 

 tinguished : first, quiet, regular arcs, slowly passing from the 

 southern horizon and disappearing in the northern one ; then, 

 bands of light of great variety of forms, ever changing place and 

 intensity ; and Lastly, the so-called corona, i.e. radiations from 

 or towards the magnetic pole. Generally the colour is an intense 

 white with a greenish hue ; with greater motions and stronger 

 radiations the prismatic colours are often seen in great intensity. 



Lieut. Weyprecht spent much time and trouble on spectral 

 observations of the auror.^, but unfortunately his spectroscope 

 was too small and imperfect. Ifc could never see more than 

 the well-known gretn line ; compared with the spectral observa- 

 tions of the Swedish Kxpedition, which were made with much 

 more perfect instruments, his observations are of no value. One 

 interesting fact with regard to the aurora> was, however-, ascer- 

 tained. It was found that upon very intense aurora: storms fol- 

 lowed almost every time ; this is proved by meteorological data, 

 and Lieut. Weyprecht thinks he is justified in the conclusion that 

 the Aurora Borealis is an atmospheric phenomenon and closely 

 connected with meteorological conditions ; he arrived at this 

 conviction through observing hundreds of aurora?, but says he 

 cannot give any positive or important reason for his conclusion. 

 ( To h€ continued. ) 



JOHN EDWARD GRAY, F.R.S. 



\1 T^E have to record the death, on Sunday morning last, 

 ^ ' at his residence in the British Museum, of Dr, J. E. 

 Gray, late Keeper of the Zoological portion of the National 

 Collection. 



Dr. Gray was born in 1800 at Walsall, in Staflbrdshire, 

 being the eldest of the three sons of Mr. S. F. Gray, a 

 chemist of that town. He was educated for the medical 

 profession, and very shortly exhibited his biological taste, 

 by writing a work on the then new "natural" arrange- 

 ment of plants. In 1S24 Dr. Gray was appointed an 

 assistant in the Natural History department of the British 

 Museum, where, with the assistance of Dr. Leach, he 

 commerced the study of zoology to such good purpose 

 that in 1840 he succeeded Mr. Children as Keeper of the 

 Zoological Collection of the Museum. At that time bio- 

 logy held but a small place in popular favour, especially 

 in the eyes of those most active in the superintendenc of 



the extension of the British Museum. Against the 

 opposing influences thus affecting his department, not 

 the least of which was the antagonism of Mr. Panizzi, 

 Di'. Gray, by bis indefatigable zeal and courage to 

 face obstacles, neiertheless succeeded in bringing the 

 national collection of osteological and skin specimens, 

 during the thirty-five years of his keepership, to so high 

 a standard of excellence, that no other museum, not even 

 Leyden itself, is equal to it. 



Most of the biological societies which now exist include 

 Dr. Gray amongst their founders or earliest members. 

 The Zoological Society owes much to him, the number 

 of papers communicated to it by him being very great. 

 He was the leading spirit of the Annals ami Magazine 

 of Natural Histo/y, and was the author of the Zoological 

 Miscellany, Knoivshy Menagerie, and other works. In his 

 Catalogue of the Mammals in the British Museum, which 

 is far advanced towards completion, is incorporated much 

 of the author's work in that direction, published originally 

 in separate short papers. 



The qualities which most distinguished Dr. Gray as a 

 naturalist were his great industry in combination with an 

 acute perception of minute distinctions. His imperfect 

 acquaintance with anatomy in many of its branches much 

 limited his generalising powers, and in some cases dis- 

 torted his view of the relative importance of character 

 based only on osteological features. To all students of 

 the groups of animals which were touched upon by Dr. 

 Gray — and there are but few that were not — that author's 

 work will be found invaluable, both from the independent 

 light which it throws on the subject, and from the careful 

 review which it gives of the previous investigations of 

 other naturalists. 



Dr. Gray was elected a Fellow of the Royal Society in 

 1832 ; he resigned the Keepership of the British Museum 

 at Christmas last. He leaves a widow, but no children. 



NFAV ORDER OF EOCENE MAMMALS 



AT the last meeting of the Connecticut Assembly, 

 February 17, Prof. O. C. Marsh made a comijtuni- 

 cation on a new order of Eocene Mammals, for which he 

 pioposed the name lillodontia. These animals are 

 among the most remarkable yet discovered in American 

 strata, and seem to combine characters of several distinct 

 groups, viz., Carnivores, Ungulates, and Rodents. In 

 Tillotheriion, Marsh, the type of the order, the skull has 

 the same general form as in the bears, but in its structure 

 resembles that of Ungulates. The molar teeth are of 

 the ungulate type, the canines are small, and in each jaw 

 there is a pair of large scalpriform incisors faced with 

 enamel, and growing from persistent pulps, as in Rodents. 



The adult dentition is as follows :— Incisors - ; canines 



3_ 



3' 



lower jaw with the skull corresponds to that in Ungulates. 

 The posterior nares open behind the last upper molars. 

 The brain was small, and somewhat convoluted. The 

 skeleton most resembles that of Carnivores, especially 

 the Ursidcc, but the scaphoid and lunar bones are not 

 united, anti there is a third trochanter on the femur. 

 The radius and ulna, and the tibia and fibula are distinct. 

 The feet are plantigrade, and each had five digits, all 

 terminated with long, compressed and pointed, ungual 

 phalanges, somewhat similar to those in the bears. The 

 other genera of this order are less known, but all appa- 

 rently had the same general characters. There are two 

 distinct families, Tillothtrida:, in which the large incisors 

 grew from persistent pulps, while the molars have roots ; 

 and the Stylinoiiontidce, in which all the teeth are root- 

 less. Some of the animals of this group were as large as 

 a Tapir. With Hyra.v or the To.x'odontia the present 

 order appears to have no near affinities. 



