12 BRITISH FRESHWATER RHIZOPODA. 



nucleoles ; contractile vesicle voluminous ; pseudopodia 

 broad and short, usually somewhat angular in outline. 



Length up to 300 /x or 400 /*,; nuclei about 10 p. in 

 diameter. 



Habitat. Damp moss. Rare. 



IRELAND. Clare Island, Mayo. 



The nuclei may be very numerous, the number, 

 according to Penard, sometimes reaching several 

 hundreds ; .the nucleoli are distinct and scattered, 

 they may number twenty but are usually about eight 

 or ten. 



The plasma usually has few inclusions, the remains 

 of ingested rotifers and a parasitic bacillus have been 

 observed ; the contractile vesicle is exceptionally 

 large and its diameter may equal one quarter of the 

 length of the organism. 



This species and A. fibrillosa Greeff together with 

 A. verrucosa Ehrenb. (A. terricola Greeff) form a 

 group the members of which are often found in moss 

 that is liable to desiccation, and it may be to this 

 circumstance that the unusually firm outer covering 

 with which they are all provided is due. Whether it 

 is a true pellicle or only a hardening of the ectoplasm 

 has been much discussed, and for a summary of the 

 various opinions the reader is referred to Penard,* 

 who after weighing the evidence comes to the con- 

 clusion that these species possess a true, although very 

 fine, pellicle. 



Specimens of A. verrucosa in a dried state sent 

 through the post from Dr. Penard in Geneva to the 

 author in America all revived after a few hours in 

 fresh water. 



The three species have characteristic nuclei ; those 

 of A. fibrillosa are spherical and contain a single 

 centrally-placed nucleole, whilst A. verrucosa has a 

 single nucleus which is ovoid and contains numerous 

 nucleoles. 



* 'Faune Rhiz. du Leman,' pp. 105-121. 



