90 ANNALS OF SCOTTISH NATURAL HISTORY 



Family DINOCHARID^E. 

 Dinocharis tetractis, Ehr. Bavelaw Moss. 



Stephanops stylatits, Milne (4). Bavelaw Moss, Duddingston Loch, 

 Hopetoun Woods, Cocklerue near Linlithgow. 



6". tenellus, Bryce (1). Discovered by Bryce in Moss from Spitz- 

 bergen in 1897, the animal has been rarely noticed since; 

 indeed, it is so small and moves so fast, that if only seen under 

 low powers it would be readily passed over as a Ciliate 

 Infusorian. I have seen it several times in Scotland, but never 

 in abundance till Mr. Evans got it in Hopetoun Woods, 

 December 1905. 



S. microdactylus, n.sp. Very small, lorica narrow, bearing towards 

 its posterior edge a long rigid curved seta ; foot long, very 

 slender, without spines, of three nearly equal segments ; 

 terminating in two excessively minute toes. 



Its total length of ^^ inch (TOO//.) shows it to be one of the 

 smallest rotifers known, being just a little less than S. tenellus, 

 which measured -^g- inch (io6/z). Bryce, it is true (1), gives 

 his species as only SO/A or ^^ inch, but Scotch examples are 

 larger. The toes are so small that under a magnification of 

 500 diameters they are scarcely perceptible. The rigidity of 

 the spine is seen when the animal turns under the cover-slip, 

 when the spine becomes strongly curved, but its angle to the 

 lorica does not change. The hood is like that of 6". tenellus, 

 but the mouth has not the very long setae of that species and 

 5". stylah/s. No eyes were seen. 



In habits it is very different from S. tenellus. Though it 

 sometimes runs pretty fast, it does not make the little automatic 

 rushes characteristic of S. tenellus, which appears to be wound 

 up to go only in a certain way. This travels about more 

 intelligently, varying its rate and manner of moving according 

 to circumstances, stopping to examine a promising corner, or 

 quietly resting in one spot for a long time, leisurely grubbing 

 with its pick among the debris, like a Mefopidia, rolling from 

 side to side on the point of its toes like a Colurus. 



Many species of Stephanops having a long median spine 

 have been described. From all of these the present species 

 is distinguished by the posterior position of the spine, which 

 is not articulated at the base, and by the slender foot with 

 minute toes. It is also a much smaller animal. According 

 to Weber (9) who sorted out the confused synonymy, and who 

 unites most of the dorsal-spined StepJianops under S. longi- 

 spinatum, Tatem (8), that species is about half as long again 

 (140 to i6o/x,). 



