164 ANNALS OF SCOTTISH NATURAL HISTORY 



P. decurvicornis, Murray. - This has some resemblance to P. 

 nemoralis, but the upper lip is of different form, the sulcus 

 between the discs being deeper, and the spurs are strongly 

 decurved. Rare, Blantyre Moor. 



P. rugosa, Bryce. A species varying to a degree unusual in the 

 genus. The skin is rugose, or nearly smooth. The eyes, 

 usually pale red, may be dark red or entirely absent. The 

 teeth, normally three on each ramus, may be only two. Some 

 of the varieties have a rounded dorsal boss on the first foot- 

 joint. This is the only instance I know of such a boss outside 

 of the genus Callidina. It also varies in colour, being often 

 hyaline, but sometimes blood-red. Generally distributed, but 

 not often abundant. Blantyre Moor, Rannoch Moor, Inver- 

 ness, Sutherland. 



P. megalotrocha, Ehr. The small spurs have a little movable joint 

 at the apex. I have never been able to see central setae on 

 the discs. These are general throughout the genus except in 

 viviparous section. Not common, Fort Augustus. 



P. hexodonta, Bergendal. There can be no doubt that the animal 

 which I identify as this species has the closest affinity with the 

 pellet-forming Callidinae. It occurred abundantly in a bog 

 pool recently, and I was enabled to make a more thorough 

 study of it. The foot is three-jointed and has three toes. 

 The corona is small, in width distinctly less than the collar, 

 with a narrow sulcus in the middle of which is a large conical 

 process. Dental formula 5-4. Rare, top of Nutberry Hill, 

 Ben Oich. Mr. Bryce has suggested that this is identical with 

 P. collaris, Ehr., and as that species is described as moulding 

 its food into pellets, the identification is probably correct. 



Rotifer tardus, Ehr. Frequent, Blantyre Moor, Fort Augustus. 



R. trisecatus, Weber. Resembling R. tardus, but with longer spurs, 

 smaller eyes, and tubercled skin. A few examples in the 

 sediment of ponds, Fort Augustus. 



R. citrinus, Ehr. Frequent in ponds, Inverness. 



R. macroceros, Gosse. Usually in colonies, in rough tubes of floccose 

 matter, Inverness. 



R. macrurus, Schrank. Common, Blantyre Moor, Fort Augustus. 



R. neptiinius, Milne. Rare, not yet recorded outside of Scotland, 

 Blantyre Moor, Inverness. 



R. vulgaris, Schrank. Common, Blantyre Moor, Fort Augustus. 



R. spicatus, Murray. Easily known by the backward pointing 

 spikes on the ventral surface of the trunk. Rare, only once 

 seen, Blantyre Moor. 



