LISTS OF FEESH- WATER EHIZOPODS. 291. 



34. Htalolampe penesteata. All rayless individuals. Occasional. 



35. AoANTHOCYSTisI With delicate, simple, unforked spincs. Occasional. 



36. Amphizonella violacea ? A single individual; for the first time observed. In 



the spheroidal form about 0.15 mm. diameter; endosarc of a deep violet hue; 

 ectosarc colorless. Animal remained nearly stationary in position, with slight 

 changes of form, and emitted from one to three digitate pseudopods, sometimes 

 blunt, sometimes pointed, even or irregular, clear, and colorless at the periphery 

 and ends, but violet internally at the base. 



37. Amceba radiosa. Occasional. 



38. A. PROTEUS ? Occasional. 



With the Rhizopods there were associated a multitude of desmids — 

 Micrasterias, Euastram, Docidium, Closterium, etc , diatoms, etc., etc. 



II. EHIZOPODS OBSEEVED IN MATEEIALS COLLECTED EST THE TEAP 

 EEGION OF EOCK HILL, BUCKS COUNTY, PENNSYLVANIA, JUNE 



27, 1879. 



a. From sediment of a ditch traversing a meadow in which grew 

 Spatter-dock, Nuphar advena. 



1. DrppiiTJGiA GLOBITLOSA. Ovoid variety, with the narrower pole truncated by the 



circular mouth, which sometimes has a short, straight, or a slightly everted rim. 

 Shell composed of fine quartz-sand or of chitinold membrane incorporated with 

 thin angular plates of quartz. Endosarc colorless. Length 0.09 mm.; breadth 

 0.06 mm. ; width of mouth 0.024 mm. Frequent. 



2. D. PTRiFOEMis. Ordinary forms, mostly small. SheU of quartz-sand. Endosarc 



in some green, in others colorless. Frequent. 



3. D. aoumuntata. Shell of chitinoid membrane incorporated with variable propor- 



tions of thin angular plates of quartz-sand. Few. 



4. D. LOBOSTOMA. Shell nearly spherical or oval, composed of angular quartz-sand; 



mouth trilobate, sometimes with a short and slightly reflected rim. Endosarc 

 greeii. Frequent. Variety with smoky-colored shell, composed of fine angular 

 sand, in shape spheroidal, oval or ovoid, and even, or mammiUary, like D. tuber- 

 eulata, WaUich; mouth six-lobed, with or without a narrow projecting rim. 

 .Length 0.132 mm. ; breadth 0.12 mm.; width of mouth 0.036 mm. Frequent. 

 Variety with shell of chitinoid membrane incorporated with variable proportions 

 of thin angular plates of quartz; endosarc colorless. Few. 



5. D. CONSTRIOTA. Of varied sizes and proportions ; yellow and colorless shells of 



qnartzsand. Frequent. 



6. D. SPIRALIS. Characteristic specimens with shell of quartz-sand. Occasional. 



7. Cbwteoptxis ACULEATA. Abundant, of considerable variety, large and small, 



mostly yellow or brown, and generally having the chitinoid shell Incorporated 

 with much sand. Variety C. ecornis. Frequent and merging into Difflvgia con- 

 stricta. 



8. Arcella vulgaris. Shell with even, convex, and with mammillated or cupped 



fundus. Frequent. 



