90 BRITISH FRESHWATER RHIZOPODA. 



Body when at rest roundish or ovoid ; at other times 

 expanded, and during progression exceedingly mobile; 

 the endoplasm a deep chlorophyllous green, with a 

 pale marginal band, varying in width, of more or less 

 clear granular ectoplasm ; the pseudopodal filaments 

 slender, branching and anastomosing, ultimately form- 

 ing a widely-spreading network, colourless. Nucleus 

 inconspicuous ; contractile vesicles (one or more) small, 

 usually occurring in the semi-transparent ectoplasm. 



The bright green colour of the endoplasm, and its 

 peculiar structure, distinguish Penardia from other 

 Grymnomyxa with which it might be confounded. The 

 predatory habits of the animal are also characteristic. 



This genus has been named in honour of Dr. Eugene 

 Penard, of Geneva, whose works on the Rhizopoda are 

 so 'well known, and whose exploration of the Swiss 

 lakes has brought to light many previously unknown 

 species. 



1. Penardia mutabilis Cash. 

 (Plate IX.) 



Penardia mutabilis CASH in Journ. Linn. Soc., Zool. XXIX 

 (1904), p. 223, t. xxvi, ff. 1, 2. 



Body when at rest roughly ovoid, with almost inert 

 branching and anastomosing pseudopodia projecting 

 from the surface at various points ; the central mass 

 opaque (semi-opaque near the periphery), without 

 definite structure; at other times compressed and 

 exceedingly mobile, the entire body expanding, elon- 

 gating and contracting incessantly, and throwing out 

 from different parts of the surface a widely-extending 

 network of fine anastomosing pseudopodia Avhich are 

 used for the capture of prey. In this mobile condition 

 the body becomes nearly transparent, and the endo- 

 plasm is seen to contain a mass, with a well-defined 

 general outline, of bright or yellowish-green corpuscles, 

 oval in shape and closely compacted, but without 

 apparent nucleus. Vacuoles appear in the ectoplasm, 

 generally near the base of the branching pseudopodia. 



