74 FEESH-WATER EHIZOPODS OF NOETH AMERICA. 



form, as when in motion, from 0.12 by 0.06 mm., to 0.6 by 0.22 mm., or 

 rarely up to 1.75 by 1 mm. Frequently about 0.33 mm. long by 0.15 

 mm. at the anterior or broader end. 



Locality. — The ooze of ponds, especially those of sphagnous swamps, 

 or of damp mossy forests. In the vicinity of Philadelphia; Delaware 

 County ; mountains of Schuylkill and Monroe Counties, Pennsylvania ; 

 vicinity of Camden ; Hammonton, Franklinville and Absecom ponds ; and 

 Budd's Lake, Morris County, and vicinity of Cape May, New Jersey; China 

 Lake, Mount Gilbert, Uinta Mountains, Wyoming Territory. 



Under the name of Pelomyxa palustris, Prof. Greeff has described one 

 of the largest and most remarkable of amoeboid animals, in certain respects 

 like Amaba villosa, but in others of more or less peculiar character. In its 

 habitual shape, movements, and gluttonous nature, it resembles the latter; 

 but ordinarily it exhibits no posterior process, and this, when existing, 

 appears to be villous only in young individuals. Instead of one, it pos- 

 sesses many nuclei scattered through the endosarc ; and rarely is there a 

 conspicuous contractile vesicle present, but in its place a variable number 

 of small ones. The granular endosarc, besides the food materials and an 

 abundance of sand, contains ordinary vacuoles, and clear globules called 

 by the author 'Glanzkorper' or shining corpuscles. The size of the animal 

 commonly is about one millimetre, but reaches to two millimetres or even 

 more 



An amoeboid form, represented in pi. V, and closely related to the 

 two forms above indicated, is rather frequent in the ooze of our ponds, 

 especially those of forest swamps. Until recently I ascribed it to Amceba 

 villosa, but the weight of evidence appears to me to make it a nearer asso- 

 ciate of Pelomyxa palustris. I am, however, uncertain whether some of the 

 specimens, especially what appear to be young individuals, which I have 

 viewed as of the same kind or species, do not really belong to the former, 

 while others may pertain to Pelomyxa. 



In most respects, the animal under consideration accords with the 

 characters assigned to Pelomyxa palustris ; but in the frequent and almost 

 constant possession of a posterior villous process, it best agrees with Amceba 

 villosa. Under the circumstances I have named it Pelomyxa villosa, and 

 have the impression that all the forms may, through later investigations, 

 be proved to be but different stages of the same species. 



