The President's Address. By Prof. P. Martin Duncan. Ill 



fying power of the complete instrument with eye-piece, tube, and 

 objective, and exposes the fallacious empirical methods hitherto 

 employed, and showing that the correct amplification can be 

 determined by the use of a very simple formula. 



The last year has shown that there has been more activity 

 amongst the Fellows of the Society in original researches and in 

 the practical employment of the Microscope. 



Mr. Michael has continued his most interesting and valuable 

 work on the Oribatidae, and now science has the advantage of 

 much correct knowledge regarding the anatomy of this interesting 

 group. 



Dr. Hudson, pursuing his admirable researches amongst the 

 Eotifera, has added three new and very remarkable species of the 

 exquisite genus Floscularia to natural history. Most of us 

 recollect the first Fhscularim that we ever saw : how out of a dull 

 looking indefinite lump a projection appeared, and how long, 

 slender, apparently never ending, threads grew on ; how these 

 slender threads radiated from certain spots and seemed as rigid as 

 bristles ; and how this most delicate creature possessed rotifer-like 

 jaws, and how the whole gradually retracted, and as it were turned 

 itself in. Some of Dr. Hudson's new forms depart, however, consi- 

 derably from the common type of Floscularia. His Floscularia 

 Jioodii (hoodii by name, cucullatus by nature !) is the largest of all 

 the rotifers, has only three lobes and possesses two remarkable 

 flexible processes placed one on each side of the summit of the 

 dorsal lobe. These have been carefully studied by Dr. Hudson, 

 because their antenna-like appearance is striking. He did not find 

 the slightest trace of setae in connection with these processes. They 

 appear to be hollow, and to communicate with two sub-spherical 

 spaces lying between the two surfaces of the dorsal lobe. Fine 

 muscular threads pass down and across them, and the animal can 

 contract and expand each independently of the other and throw 

 them into all kinds of positions. The upper end of each seems 

 to be separated partly from the remainder by a constriction, from 

 which a muscular thread runs down to the base. These movable 

 processes do not both project invariably when protrusion of the 

 animal occurs from its case, and they appear to discharge a granular 

 matter. There is a point of interest also in the long filamentous 

 setae. Dr. Hudson states that, the thickened rim of the three lobes 

 carries a double fringe of setae, set just as they are in F. trifolium, 

 the larger row stretching outwards and the smaller inwards ; and 

 he has on several occasions seen a rapid flicker run all along the 

 smaller setae, not constant or regular enough to produce the pheno- 

 mena of " rotation," but still a very obvious motion of each separate 

 seta. The gape of the mouth-funnel of this rotifer alters constantly 

 and closes by means of its many muscular threads. It has two 



