W. H. HARRIS OX MARINE MICROSCOPIC VEGETABLE ORGANISMS. 161 



Achhja reticulata. — This is a very distinct, robust, and exceedingly 

 handsome species. 



It occurs in fragments of shell and foraminifera of the genus Operciilhia ; 

 when suitably placed for free development it usually forms a circular patch, 

 frequently attaining the one-twentieth of an inch in diameter. 



The filaments are fairly large, but they are irregular in size ; branches are 

 produced at frequent intervals, which soon coalesce and form a perfect 

 network of filaments arranged in graceful curves ; the surface is very 

 liberally furnished with short, rather stout appendages (excretory ducts), 

 the apertures of which vary in form and size, giving the organism the 

 appearance of being decorated with minute gems. 



Rather plentiful in material from Java Sea and Macassar Straits, 45 

 fathoms; but not found in any dredgings outside this area. Plate 10, 

 Fig. 11 X 180. 



Achlya JIahclUformis. — This is a rather small organism, but its distin- 

 guishing features are very well defined. It may be described as consisting 

 of two distinct parts — viz., a tubular portion, which gradually passes into 

 an expanded part. 



The tubular portion frequently perforates the enclosing fragment, entering 

 on one side and passing in an oblique dii'ection to the other surface ; 

 occasionally it may reappear on the same side it entered, forming in its 

 course the segment of a circle ; but however it behaves in this respect, it 

 always expands as it reaches the surface, and ultimately assumes a fan-like 

 form with a few growing points slightly in advance of the main body. 



The surface of the expanded portion is plentifully furnished with rather 

 short, stout appendages ; the tubular part is also provided with similar 

 organs for some distance from the expanded part, but more sparingly, the 

 portion near the original point of entry being destitute. 



Very frequently the surface is eroded to some extent, thus exposing the 

 interior of the organism. 



Rather rare. Appears to be a comparatively shallow-water form ; coral- 

 reef material has furnished the majority of the specimens. Plate 10, 

 Fig. 12 X 300. 



The following species have been dealt with by Mr. Waller : — 

 Lacuna ampullieformis, 



„ S2}orangifera. 

 AcJdya iierforans. 



„ villosa. 

 Saprolegnia varniefi-sts. 

 Varneia villosa. 



