J 54 



NATURAL SCIENCE. 



March, 



distance above and parallel to its edges. These pedal grooves rise 

 slightly at the tail and meet above it, the point of their junction being 

 often marked by a local deepening of the groove, the "caudal 

 mucous pore." This last has frequently been used as an important 

 factor in classification, whereas it is merely an occasional extra 

 development. 



The Aulacopoda will thus form a group equivalent to the Agnatha 

 (so-called, including the Selenitidae), or to the group composed of the 

 Helicidae, Bulimulidae, Cylindrelidae, Pupidae, and Achatinidae, for 

 which last Pilsbry proposes the name Holopoda. 



The New Photography. 



So much has appeared already in the daily and weekly Press 

 that we have little more to do than to call attention to the specimen 

 of the new photography which, by the kindness of Mr. Campbell 



Photograph of the Skeleton of a Living Frog. 



(Taken by A. A. Campbell Swinton, and reproduced from The Nezv Light, 

 published for The Photogram, by Dawbarn & Ward). 



Swinton and the editors of the Photogram, we are able to reproduce in 

 these columns. The exact nature of the rays which Professor 

 Roentgen has discovered to be capable of passing through substances 

 that are opaque to ordinary light is still far from certain. It seems 

 as yet to be more probable that they are undulations of some kind, 

 and not, as has been cleverly suggested, a material emanation of 

 small particles. At present, the great difficulty in employing the 

 new process is the absence of a means of focussing the rays. The 



