172 MR JAMES MURRAY ON 



P. jiaviceps, n. sp., Bryck. (Plate I. figs. 1« to If) 



See description further on. 



One of the commonest Bdelloids in Scotland, in lochs, streams, bogs, etc. Too 

 common in lochs to call for details of distribution. Ubiquitous though it is, it yet 

 evinces a preference for pure waters.* 



The spurs are somewhat variable. In fig. If I have shown the typical short, blunt 

 spurs ; in fig. id, a longer, straighter pair ; in fig. le, a peculiar form often found in 

 animals otherwise typical ; they are placed close together, incurved, acute. 



An abnormal example, with flame-shaped ' ligule ' between the discs, was found in 

 Loch Ness. 



P. rugosa, Bryce (9). 



Extremely variable ; the type has dental formula 3/3, and red eyes. A variety in 

 Loch Morar had no eyes, teeth 2/2, and a boss on the first foot-segment, as in many 

 Callidinse. 



P. acuticornis, Murray (37). (Figs. 3 and 9a to 9d.) 



Occasionally found in lakes, though more at home in bogs and ponds. The 

 original figure being somewhat poor, better drawings since obtained are here given 

 (figs. 9a, 9b). In dorsal view a graceful animal, the light corona, thin neck, and slender 

 foot tapering to the narrow, acute spurs all impart an appearance of lightness. This 

 appearance is deceptive. In lateral view (fig. 9b) it is seen that it has none of the 

 dorso-ventral flattening which is usual in Bdelloids. The central part of the trunk is 

 very deep from front to back — in fact, quite barrel-shaped. This bulk of paunch is 

 necessitated by the very voluminous stomach. The head and foot are really light. In 

 keeping with its heavy trunk, the gait is slow and deliberate. The transverse ventral 

 folds between the segments are distinct and equidistant, as the animal takes the 

 forward step. 



P. laticeps, Murray (39). 



Though discovered on insect larvae, this is now known to be the commonest 

 p;ir;isite on Gammarus in Scotland. This led to a suspicion that it might be identical 

 with Giglioli's Callidina parasitica, which he found so common on Gammarus. 

 Giglioli (15) says the corona is small, and figures it as extremely small. It is true 

 that the measurement he gives for a small example makes it very large, but there 

 are contradictions in his other measurements ; so we are justified in concluding that a 

 deliberate statement, and still more deliberate drawing, are conclusive. 



The most obvious distinctive character of P. laticeps is the great spreading corona. 

 The pointed end of the last foot-joint of C. parasitica is unlike anything in P. latic<j>s. 

 The antenna (calcar) is said to be large and well developed. These terms are relative, 



* While these notes are in press, P.flaviceps has been found in abundance among moss collected by Prof. Forel in 

 t li>- Lake of Geneva. 



