196 FRESH-WATER RHIZOPODS OF NORTH AMERICA. 



Pamphagus hyalinus is a peculiarly delicate and sensitive creature, and 

 readily undergoes decomposition. In repeated instances, I have observed 

 the animal project from the mouth of the shell portions of the sarcode, which 

 would gradually swell up and become more or less filled with different-sized 

 vacuoles, as seen in figs. 15-17. The projected protoplasm would sometimes 

 increase to more than half the bulk of the animal in its normal condition. 

 Suspecting that this condition was a preparatory step to segmentation, I 

 was led to watch patiently several individuals for some hours to learn the 

 result, which however, in each case, proved to be decomposition or death. 



PAMPHAGUS CURVUS. 



Plate XXXIII, figs. 11, 12. 



Animal retort-shaped, or ovoid with the prolonged narrower pole 

 curved, and with the body in transverse section circular. Mouth inferior, 

 terminal, circular. Shell transparent, colorless or pale yellowish, structure- 

 less. Sarcode continuous with the interior of the shell, and having the 

 nucleus as in P. mutdbilis. Pseudopods likewise as in the latter. 



Size. — From 0.044 mm. in length by 0.028 mm. in breadth to 0.06 mm. 

 in length by 0.036 mm. in breadth. 



ioca^«^«/. -^Vicinity of Philadelphia, in the superficial ooze of ponds. 



In a few instances I have met with a small rhizopod resembling in 

 structure and habit the Pamphagus mutabilis, but with a shape like that of 

 Cyphoderia. The shell is structureless and closely adherent to every part 

 of the surface of the interior sarcode, from which it appears to be as insep- 

 arable as in Pamphagus mutabilis. Figs. 11, 12, pi. XXXIII, represent two 

 such specimens. 



PAMPHAaUS AVIDUS. 



Plate XXXIII, fig. 10. 



Body oval or ovoid, in transverse section circular, wider at the oral 

 pole; naouth small, circular, expansile and contractile. Nucleus, etc., as in 

 P. mutabilis. 



8ise. — From 0.148 mm. to 0.22 mm. in length by 0.12 mm in breadth. 



Lomlity.-^QQAax swamp of Atco, New Jersey. 



In September, 1877, in some material collected in pools in the cedar 



