290 FRESH-WATER EHIZOPODS OF NORTH AMERICA. 



13. Aecella vulgaris. Varieties with both evenly convex and mammillated fundus. 



Occasional. 



14. A. discoides. Frequent, and of varied sizes. 



15. A. miteata. Rare. 



10. Heleopeea picta. Frequent. 



17. LI. peteicola. Occasional, but more frequent than usually. In some the shell 



was incorporated with sand the greater part of its extent. 



18. Quadrula symmetrica. Occasional. 



19. Centeopyxis aculeata. Frequent and varied. Variety C. ecomis grading by 



intermediate ones into Difflugia constricta. Frequent. 



20. Hyalospeenia papilio. Frequent, but not so abundant as commonly observed 



in sphagnum from similar localities. 



21. H. elkgans. Frequent. 



22. Euglypea cieiata. Generally small, and very variable in size; larger ones 



occasionally devoid of cils. Large empty shells with twelve blunt, thickened 

 denticles to the mouth; plates of the shell distinctly hexahedral and in close 

 juxtaposition, with no signs of being oval and overlapping at the contiguous 

 borders. Variety E. strigosa. Abundant. 



23. E. cetstata. Frequent, A small individual with four conspicuously thickened 



denticles to the mouth of the shell was 0.054 mm. long, 0.018 mm. broad, and 

 0.009 mm. at the mouth. 



24. E. braceiata. Occasional. Two empty shells adhered at the mouth, as if when 



alive the animals had been in conjugation. The shells had each six acute 

 denticles to the mouth, the plates of which were not perceptibly thicker than 

 elsewhere. The plates generally were nearly round, and overlapped at the 

 contiguous borders, so as to include hexahedral spaces. One shell was pro- 

 vided with a pair of lateral hair-like spines as usual, but the other shell was 

 spineless. Size of the spinous shell 0.108 mm. long, 0.036 mm. broad, and 0.0135 

 mm. at the mouth ; of the spineless shell 0.102 mm. long, 0.036 mm. broad, and 

 0.012 mm. at the mouth. 



25. E. mucronata. Occasional. Several without the mucro, but otherwise the same. 



26. Assulina seminulum. Frequent, Several large and uncolored observed besides 



the ordinary brown variety. 



27. Sphenoderia lenta. Frequent, Observed several with the border of the mouth 



minutely but feebly denticulate. 



28. S. macrolepis. Frequent. A species for the first time observed, with characters 



as follows: small, compressed pyriform, with the neck gradually prolonged from 

 the body. The latter with a pah of wide hexagonal plates across the intermedi- 

 ate portion of the broader sides of the shell. Length 0.030 mm. ; breadth 0.024 

 mm.; width of mouth 0.012 mm. See woodcut, page 232. 



29. Cyphodeeia ampulla. Few. 



30. Trinema enceelys. Numerous and of many varieties. Several bright brown 



shells, like those of Arcella, for the first time observed. 



31. Placocista spinosa. Rare. 



32. Psetjdodipflugia gracilis. Like fig. 21, pi. xxxiii. Length 0.045 mm.; breadth 



0.03 mm., and at mouth 0.018 mm. Occasional. 



33. Clateeulina elegans. Dead shells, or individuals in the quiescent state. One 



observed in the latter condition containing five nucleated balls, 0.009 mm. in 

 diameter. Occasional. 



