AND ITS ALLIES. 223 



Ehrenberg states that P. aculeata is periodically viviparous. 

 In all my experience of all three species I have found no con- 

 firmation of this, the species being uniformly viviparous. 

 Janson (13) also expresses doubt of Ehrenberg's statement. 



Ehrenberg may possibly have mistaken the embryo at an 

 early stage for an egg, but it is not yet demonstrated that the 

 mode of reproduction is invariable. 



P. tuberculata, Gosse (11), (Plate 15, Figs. 3, 4) I consider 

 to be not even a variety, but merely a condition of P. acrostyla. 

 The protective secretion? is particularly abundant, and when 

 the animal is dormant it forms a very thick coating, consisting 

 of a number of plates, corresponding to the longitudinal and 

 transverse folds of the skin of the trunk. This coating may 

 persist for a long time after the animal resumes activity, but 

 can be rubbed off by rolling under a cover-slip. 



Both the type and the tubercled form are among the commonest 

 rotifers in Scotland, and occur in many situations. They are 

 especially frequenters of peat bogs, and live well in very dirty 

 water. P. tuberculata has been found living in a small bottle 

 which had been completely filled with evil-smelling mud and 

 tightly corked for twelve months. 



Philodina spinosa (Bryce), (1), (Plate I. Figs. 5, 6). 



Bryce, " CaMdina spinosa" (1) 1892, p. 22. "Longitudinal 

 skinfolds and those marking trunk segments armed with very 

 short prickle-like points set closely together, the angles marked 

 with rather longer points. A short spine on centre of ventral 

 margin and a longer one at each lateral angle of anterior edge of 

 first trunk segment. Spurs rather long and of peculiar shape ; at 

 first parallel, they are bent outwards at a right angle and thence 

 incurved, so that each describes a quarter-circle, the point being 

 directed downwards and backwards." 



I have quoted Mr. Bryce's diagnosis in full, because it 

 illustrates a characteristic of all his work. However incomplete 

 his descriptions may sometimes of necessity be, they are so accurate 

 that the animals can always be readily recognised again. 



In this instance he only saw a single example, which was very 



Journ. Q. M. C, Series II.— No. 62. 17 



