W. H. HARRIS ON MARINE MICROSCOPIC VEGETABLE ORGANISIklS. 141 



remains, in which I discovered only one of the vegetable organisms. 

 Again a half-pound of dredgings from Batavia (Java) gave only 

 a few grains of suitable material, in which but two fragments 

 were deemed worthy of preservation. Java sea dredgings outside 

 the limits of fine mud deposit simply teem with the little plants. 

 Dredgings from Cebu, Phihppine Islands, when taken from the 

 Hyalonema ground at a depth of 120 fathoms contain a smaller 

 percentage of mud than the preceding, forming however a large 

 proportion of the bulk, and the vegetable organisms are very 

 sparingly represented, while tolerably pure sand from a beach 

 in the same locality affords a plentiful supph'. 



My impression is that the mud protects the fragments of 

 shells, etc., from the attacks of the plants. 



I have several slides of sponge spicules, prepared from specimens 

 dredged in a living condition, but not a single example of the 

 little plants can be detected therein. 



I have a note of a very interesting case, but unfortunately I 

 appear to have lost the specimen. The concave side of a shell 

 was bored for some depth by a boring mollusc, the shell was 

 invaded by the vegetable organisms, and one plant took the 

 direction of the hole ; it then descended and ascended its sides, 

 passing on as though no obstruction had occurred. This is a 

 curious example of lack of judgment on the part of the boring 

 mollusc, but I cannot help feeling much obliged to it for assisting 

 me with evidence confirming the view I have taken that the 

 cast-off shell was invaded by the plant subsequent to the excava- 

 tion by the mollusc. 



Until proof of the incorrectness of my theory can be adduced 

 I am disposed to regard these as organisms finding a suitable 

 habitat in dead organised material : hence I use the term " in- 

 vading " in preference to " parasitic." 



Bibliography. 



The following list of Uterature on the subject of this paper is 

 as far correct as I have been able to ascertain. Nearly all the 

 papers are scattered through various reports of scientific societies, 

 for copies of which I am indebted to my private friends, and also 

 to the excellent work on Fossil Plants, by A. C. Seward, M.A., 

 F.G.S., Cambridge University Press, 1898, which has just been 

 published. 



