PAULINELLA CHROMATOPHORA. 67 



and devoid of food-particles, one or two curved 

 chromatophores always present; one contractile 

 vesicle usually visible ; pseudopodia few, filose, 

 straight and radiating. 



Length 20-32 p ; diameter 14-23 /x ; aperture 3-4 p. 



Habitat. Submerged vegetation in fresh- and 

 brackish-water. 



ENGLAND. Sprinkling Tarn, Cumberland ; Easdale 

 Tarn and Windermere, Westmorland ; and Highlow 

 Tarn and tarn on Clarfe Heights, Lancashire (Brown). 



SCOTLAND. Loch Ness, Inverness-shire (Penard). 



The test of this species is of a unique character and 

 the horse-shoe-shaped chromatophores which accord- 

 ing to Lauterborn and Penard are always present 

 have never been found elsewhere ; these bodies appear 

 to be a species of Alga living in symbiotic relationship 

 so close that they act as true chromatophores; their 

 colour is a bright blue-green and they undergo trans- 

 verse division. 



The absence of all trace of food-particles in some 

 600 or 700 individuals observed by Lauterborn and 

 Penard points to the chromatophores as having nutri- 

 tive functions. 



Multiplication appears to take place by sporulation, 

 as Penard found many half-grown forms (12-14 /A in 

 length) which give rise by repeated division to full- 

 sized individuals ; some of the small forms were 

 observed in conjunction. 



The colour of the test is probably due to a thin 

 chitinous lining which becomes darker with age. 



Var. pulchella (G. S. West) var. nov. (PL XLIV, 

 figs. 5 and 6.) 



Sphenoderia pulchella 



WEST in Jm. Linn. Soc., Zool. XXIX (1903), pp. 115-116, pi. xiii, 

 ff. 13-15. 



Test larger than in the type and similar in con- 

 struction but having six plates in each transverse row 



