450 



NATURE 



[Sepi. 20, 1877 



The amphibia are so nearly allied to the ganoid fishes, that we 

 can hardly doubt their descent from some member of that group. 

 With our present limited knowledge of the extinct forms, how- 

 ever, it would be unprofitable to attempt to trace in detail their 

 probable genealogy. 



The authors to whom especial credit is due for our knowledge 

 of American fossil fishes and amphibians, are Newberry, Leidy, 

 Cope, Dawson, Agassiz, St. John, Gibbes, Wyman, Red field, 

 and Emmons, ,ind the principal literature of the subject will be 

 found in their publications. 



Reptiles and birds form the next great division of vertebrates, 

 the sauropsida, and of these *he reptiles are the older type, and 

 may be first considered. While it may be stated with certainty 

 that there is at present no evidence of tlie existence of this group 

 in American rocks older than the carboniferous, there is some 

 doubt in regarii to their appearance even in this period. Various 

 foot-prints which strongly resemble those made by lizards, a few 

 well preserved remains similar to the corresponding bones in that 

 group, and a few characteristic specimens, nearly identical with 

 those from another order of this class, are known from American 

 coal measures. These facts, and some others which point in the 

 same direction, render it probable that we may soon have 

 conclusive evidence of the presence of true reptiles in this for- 

 mation, and in our overlying perinian, which is essentially a part 

 of the same series. In the permian rocks of Europe, true reptiles 

 have been found. 



The mesozoic period has been called the age of reptiles, and 

 during its continuance some of the strangest forms of reptilian 

 life made their appearance, and became extinct. Near its com- 

 mencement, while the triassic shales and sandstones were being 

 deposited, true reptiles were abundant. Among the most 

 characteristic remains discovered are those of the genus Belodon, 

 which is well known also in the trias of Europe. It belongs to 

 the thecodont division of reptdes, which have teeth in distinct 

 sockets, and its neare-t affinities are with the crocodilia, of which 

 order it may be considered the oldest known representative. In 

 the same strata in which the belodonts occur, remains of dinosaurs 

 are found, and it is a most interesting fact that these highest of 

 reptiles should make their appearance, even in a generalised 

 form, at this stage of the earth's history. The dinosaurs, although 

 true reptiles in all their more important characters, show certain 

 well marked points of resemblance to existing birds of the order 

 Ratitce, a gioup which includes the ostriches ; and it is not im- 

 probable that they were the parent stock from which birds 

 originated. 



During triassic time, the dinosaurs attained in America an 

 enormous development both in variety of forms and in size. 

 Although comparatively few of their bones have as yet been 

 discovered in the rocks of this country, they have left unmistak- 

 able evidence of their presence in the loot-prints and other 

 impressions upon the shores of the waters which they frequented. 

 The triassic sandstone of the Connecticut Valley has long been 

 famous for its fossil foot-prints, especially the so-called "bird- 

 tracks," which are generally supposed to have been made by 

 birds, the tracks of which many of them closely resemble. A 

 careful investigation, however, of nearly all the specimens yet 

 discovered, has convinced me that there is not a particle of 

 evidence that any of these fossil impressions were made by birds. 

 Most of these three-toed tracks were certainly not made by birds ; 

 but by quadrupeds, which usually walked upon their hind feet 

 alone, and only occasionally put to the ground their smaller 

 anterior exiremities. I have myself detected the impressions of 

 these anterior limbs in connection with the posterior foot-prints 

 of nearly all the supposed "bird-tracks" described, and have 

 little doubt that they will eventually be found with all. These 

 double impressions are precisely the kind which dinosaurian 

 reptiles would make, and as the only characteristic bones yet 

 found in the same rocks belong to animals of this group, it is 

 but fair to attribute all these foot-prints to dinosaurs, even 

 where no impressions of fore-feet have been detected, until some 

 evidence appears that they were made by birds. I have no 

 doubt that birds existed at this time, although at present the 

 proof is wanting. 



The principal genera of triassic reptiles known from osseous 

 remains in this country are, Amphisaiirus [Megadactylu^), from 

 the Connecticut Valley, Bathy^nathits, from Prince Ei (ward's 

 Island, Bc/oJon and Ciepsysaiinis. Other generic names which 

 have been applied to foot-prints and to fragmentary remains, 

 need not be here enumerated. A few remains of reptiles have 

 been found in undoubted Jurassic rocks' of America, but they 

 are not sufficiently well determined to be of service in this 



connection. Others have been reported from supposed Jurassic 

 strata, which are now known to be cretaceous. It will thus be 

 seen that, although reptilian life was especially abundant during 

 the triassic and Jurassic periods, but few bones have been found. 

 This is owing in part to the character of most of the rocks then 

 formed, which were not well fitted for preserving such remains, 

 although admirably adapted to retain foot-prints. 

 ( To be conlinued. ) 



ON NOCTURNAL INCREASE OF TEMPERA- 

 TURE WITH ELEVATION^ 

 'TWILL the year 1862, when my first experiments were made 

 -*■ by the use of the balloon, our knowledge of the tem- 

 perature of the air was almost entirely confined to within 

 four or five feet of the earth's surface, and the theory that the 

 temperature was always lower at high elevations, and that the 

 decrease of temperature with increase of elevation was at the 

 rate of 1° Fahrenheit for every 300 feet of elevation, was gene- 

 rally received and acted upon. These theories were found not to 

 be at all times true, and the assumption of the decrease of 1° of 

 temperature in every increase of 300 feet ) ; elevation was proved 

 to be erroneous in every balloon ascent I nave made ; in some a 

 decrease of 1° and more than 1° was experienced within too feet, 

 and there is no doubt that, considering °the quickness of motion 

 on leaving the earth, the decrease at such times was really 2° or 

 3°, or more, within the space of 100 feet. 



In some of the accents a difference of 10° was met with within 

 1,000 feet of the earth, whilst in others but little or no difference 

 was experienced even to heights exceeding 1,000 feet. 



Towards the end of my iSalloon experiments it was evident 

 that a very large number more were necessary, and in my last 

 report I said : — 



From all the experiments made it would seem that the decrease 

 of temperature with increase of elevation is variable throughout 

 the day, and variable in different seasons of the year ; that at 

 about sunset the temperature varies but very little for a height of 

 2,000 feet ; that at night with a clear sky the temperature in- 

 creases with elevation ; that at night with a cloudy sky there 

 was a small increase of temperature as the height increased ; 

 that in the double ascent of May 29, 1866, the one just before 

 and the other after sunset, it would seem that after radiation 

 from the earth began, the heat passes upwards till arrested where 

 the air is saturated with vapour, when a heat greater by 5° was 

 experienced after sunset than at the same elevation before sunset. 



This was the state of our knowledge when M. Giffard most 

 kindly placed the great " Captive " balloon, located at Ashburn- 

 ham Park, Chelsea, near London, at my disposal for a series of 

 experiments. 



This balloon could ascend to the height of 2,000 feet on a 

 calm day ; its rate of ascension could be regulated at will ; it 

 could be kept stationary at any elevation, and experiments could 

 be repeated several times in the day. 



On two different days I ascended nine times on each day ; 

 there was a decrease of temperature with increase of elevation 

 at every ascent, but, different in amount at every hour, being less 

 and less as the day advanced towards sunset. The results of the 

 experiments are shown in the following table, showing the 

 amount of decrease of temperature per 100 feet of elevation, at 

 different hours of the day with a clear sky, and a cloudy sky, as 

 found by experiments with M. Giffard's captive balloon. 



« Abstract of a paper read at the Ha r« meeting of the French Associa- 

 tion by Mr. James Glaisher, F.R. S. 



