324 DAVID BRYCE ON 



study which has completely revolutionised our knowledge of 

 Bdelloid Rotifera. 



The small trochi and the upper lip resemble those of H. con- 

 stricta, and the general appearance when feeding is very similar. 

 I think it is a rather smaller form than its commoner relative and 

 rather more sturdy in build. The mastax and the brain are in 

 the usual position, the rami have each two teeth, the upper lip 

 is moderately high and centrally is obtusely pointed ; the spurs 

 are small cones set closely together, moderately divergent, but 

 less so than in its relative. 



The figure (fig. 5) is from an English example. 



Length about 200 /^ to 255 /j.. 



Habitat. — Ground moss. 



Macrotrachela aculeata Milne. 

 Several examples of this species, which is exceedingly variable, 

 were of the ordinary type found in Britain. It is a very widely 

 distributed species, but occurs only in small numbers. 



Macrotrachela Ehrenbergii (Janson). 

 Only recognised among the wet moss from the gatherings 

 Z 1 and 2. Besides the adults, some of the characteristic spinous 

 eggs were seen. 



Macrotrachela concinna (Bryce). 

 Several specimens were seen in the washings from the " dry 

 tundra" (L 25). 



Macrotrachela hahita (Bryce). 

 This species occurred in five difierent gatherings. It is one 

 of the most widely distributed of moss-dwelling Bdelloida, and 

 is extremely hardy. It is exceedingly variable in minor details. 

 Murray has recorded its presence in the lakes near Cape Eoyds 

 (6), where the local form was noteworthy for the deep crimson 

 colour of the stomach. The Spitsbergen examples seemed 

 typical in all respects. 



Macrotrachela multispinosa Thompson. 

 Only one example of this most variable species was detected. 

 It had the ordinary spines of medium length. 



