64 



KNOWLEDGE & SCIENTIFIC NEWS. 



[April, 1904. 



change of the latter, I am more disposed to call the 

 Mesozoic forms primitive creodonts, and to consider 

 creodonts as the ancestors of marsupials, rather than 

 vice vena. 



The whole question is, however, absolutely bristlint; 

 with difficulties and uncertainties, and involves the dis- 

 cussion of a number of technicalities which cannot 

 possibly be touched upon here. 



With this, then, I must lea\e the subject, merely 

 adding that after having traced the specialised modern 

 Carnivora into early types closely allied to the primitive 

 Creodontia, and ha\ing also pointed out the existence of 

 a near affinity between the latter and the carnivorous 

 marsupialia, the question naturally arises whether the 

 middle Mesozoic mammalian forerunners of these groups 

 may not themselves be the descendants of the carnivor- 

 ous mammal-like reptiles (theriodonts) of the early part 

 of the same epoch, which have a typical carni\orous 

 type of dentition. If so, the dog and civets of our own 

 day have a truly ancient pedigree. 



Is there Snow on the 

 Moon ? 



A Study of the Lunar Apervrvirves. 



I5v E. Walter MArxL.F.R, F.R.A.S. 



Tin: principal object in the accompanying Plate, which is 

 reproduced from one of the superb photographs taken by 

 MM. Loewy and Puiseux, with the great equatorial 

 coude of the Paris Observatorj', is the range of the 

 lunar Apennmes, by far the grandest mountain 

 chain upon the moon, and the one which, at first 

 sight at least, most stronLrly resem- 

 bles those of our own earth. It is 

 shown in its entire length of more 

 than 400 miles from the fine ring- 

 plain Eratosthenes, in the extreme 

 right-hand upper corner of the 

 Plate, which forms the termination 

 of the range to the south, down to 

 the grand promontory of Mount 

 Hadley, more than 15,000 feet in 

 height, in which it ends towards 

 the north. About halfway between 

 the two extremities of the range is 

 the magnificent headland of Mount 

 lluyghens, according to Schmter 

 nearly 21,000 feet in height, the 

 highest summit on the moon with 

 the exception of some of the peaks 

 on the ramparts of the ring-plains 

 of the south polar cap. A third 

 great promontory. Mount Bradley, 

 lies nearly midway between Mount 

 Huyghens and Mount Iladley and 

 reaches a height of about 16,000 ft. 

 The highland region, of which 

 the Apennines form the north- 

 eastern face, is roughly triangular 

 in shape. By far the loftiest and 

 steepest face is that overlooking the 



great Mare Imbrium towards the east. The north-west- 

 ern face looks over the Mare Serenitatis, whilst the Sinus 

 .■Estuum and the Mare \'aporum bound the region on 

 the south. 



The area of the Plate is not one which includesm any 

 of the circular formations so typical of the moon, but 

 some of those which are shown are very striking. Three 

 great ring-plains are seen on the floor of the Mare Imbrium. 

 These, in order of size, are Archimedes, the largest and 

 most eastern, Aristilles, the most northern, and Autoly- 

 cus, the smallest of the three, just opposite the broad 

 gap which separates the Apennines from the Caucasus. 

 On the opposite side of this opening, and slightly further 

 from it, the celebrated crater Linne is seen as a small 

 white spot on the floor of the Mare Serenitatis. Toward 

 the extreme upper left-hand corner of the Plate, near the 

 border of the same Mare, stands the bright crater Sul- 

 picius Gallus, and amongst the actual highlands of the 

 Apennines are the two craters Conon, just behind Mount 

 Bradley, and Aratus, a little further north towards Mount 

 Hadley. These seven are the most notable circular 

 formations in the Plate. In general, the lunar mountains 

 take the form of rings or polygons, as in the case of these 

 se\en objects, and do not make continuous chains as on 

 the earth. To this rule the Apennines constitute the 

 most conspicuous exception, but a detailed exanrination 

 of them shows that the differences between them and 

 the great terrestrial ranges are numerous and significant. 



The first feature of the Apennine highlands to claim 

 attention is the nearly triangular form of the area they 

 cover. This is a necessary consequence of the roughly 

 circular form of the great Maria which border them. 

 Wherever we have a number of circular depressions con- 

 tiguous to each other, the more elevated interstices must 

 necessarily approximate to triangles. .And this being the 

 case, it follows that the forms of the highlands ha\'e been 

 determined by the Maria and not the reverse. In other 

 words, the highlands existed first and acquired their 

 present outlines through the later formation of the 

 surroundinij Maria. 



Ma rr 

 ■ Ji'rriii/aiis 



Arc/ianedes 



Jristilles 



