152 FRESH-WATER RHIZOrODS OF NORTH AMERICA. 



with many other rhizopods, I observed a Nebela, agreeing with the former, 

 except that it had a curved or retort-shaped shell, as represented in the ad- 

 joining woodcut. It was a living, active individual, and the only one of 

 the kind detected. The shell was composed mainly of circular plates of 

 variable size. Its length was 0.15 mm. ; its greater breadth 0.072 mm., 

 and its less breadth 0.036 mm. 



NEBELA FLABELLULUM. 



Plate XXIII, figs. 8-19. 



Diffluyia (Nebela) flabellulum. Leidy: Proc. Ac. Nat. Sc. 1874,157. 



Nebela flabdhdum. Leidy : Proc. Ac. Nat. Sc. 1876, 118, figs. 6,7; 1877,264. 



Shell compressed pyriform or spheroid, usually broader than long, 

 sometimes as long as or longer than the greater breadth ; transverse section 

 oval, with rounded angular poles ; neck short or none ; mouth transversely 

 oval, slightly convex downward in the long diameter. Shell in color and 

 structure like that of Nebela collaris. Sarcode and pseudopods like those of 

 the latter. 



Size.— Length 0.068 mm. to 0.096 mm.; breadth 0.072 mm. to 0.104 

 mm. ; thickness 0.032 mm. to 0.048 mm. ; mouth from 0.024 mm. by 

 0.012 mm. to 0.02 mm. by 0.012 mm. 



Locality. — Sphagnous swamps of Pennsylvania and New Jersey. 

 Tobyhanna, Pocono Mountain, Monroe County ; Broad Mountain, Schuyl- 

 kill County; Swarthmore, Delaware County, Pennsylvania; Absecom, 

 Longacoming, Kirkwood, and other places in New Jersey. 



TVehela flabelluliini, represented in figs. 8-19, pi. XXIII, may be 



regarded as a variety of N. collaris in which the breadth in one direc- 

 tion is greater than the opposite one, and approaches nearly or exceeds 

 the length. It is not so common as the characteristic varieties of the 

 latter, but in some localities occurs abundantly. It is a beautiful object 

 as ordinarily seen, and reminded me of a delicate lace-covered fan. Usually, 

 as it lies in the field of the microscope, it presents a broad pyriform outline, 

 with convex fundus, and the sides more or less inflected, so as to produce 

 a neck of moderate length. Sometimes the sides slope in straight lines, so 

 as to leave no distinction of body and neck. Occasionally, also, specimens^ 

 occur in which there is no prolongation of the oral pole, so that the shell 

 is slightly oblate spheroidal in outline, as seen in tig. 15. 



