IO 



M \ definition ol a species, which 1 commend to evolution- 

 ists and transformists of the Darwin school, is that " A 



re know n, is the transient form of a living organism 

 which differed from it in the past and will differ again from it in 



the future. All that lues, and, I may add. also all that has no 

 life, <>n this earth is changing and being modified. N I ng is 

 probably at a standstill, fixed or immutable, in the univ< 

 I he laws which regulate the gradual transformation of | 

 and animals are ot the highest interest to the naturalist, and 

 should be carefully observed and worked out by him whenever 

 ii)le. 



I stated before this digression that I had added twenty- 

 new forms to the list of Campy lodisci. These comprise 

 six which will shortly he published by Dr. Leuduger-Fortmorel 

 in a catalogue of the Diatoms of the Mala) Archipelago which 

 he has prepared; one species was named by Greville in Mr. 

 Hard man's collection, hut has not been made public to this 

 day, while several others have been figured by Ad. Schmidt in 

 \ilas without names having been given them. The remain- 

 are of my own manufacture, based upon specimens kindly 

 d at my disposal by many friends of congenial tastes. 

 Most of these have since been generously offered to me and 

 aie now in my cabinet. 



The Genus Campylodiscus 



was established as long ago as 1841 by Ehrenberg, and has been 

 accepted by all subsequent naturalists. He characterised it by 

 the twisted shape of. the valves. Modern diatomists have, how- 

 ever, restricted it to such Diatoms as have a frustule formed of 

 two saddle-shaped \al\ts, which are placed at right angles to 

 each other. 



In side or valvular aspect the valves appear circular, rotundo- 

 oval, or very broadly elliptical. The front view, or connective 



zone aspect, is little developed and perplexing to the microsco- 

 pisl until the (tossed position of the valves has been fully 

 < omprehended. 



