158 FRESH- WATER EHIZOPODS OF NORTH AMERICA. 



NEBELA ANSATA. 



Plate XXV, figs. 1-8. 



Difflngia (Nebela) ansata. Leidy: Pr. Ac. Nat. So. 1874, 156. 

 Nebela ansata. Leidy: Pr. Ac. Nat. Sc. 1870, 118, fig. 14. 



Shell compressed pyriform, with a pair of lateral conical offsets diverg- 

 ent upwardly from the neck, but in other respects, in structure, color, and 

 in the shape of the mouth, as in Nebela collaris. Sarcode likewise as in the 

 latter. 



Size. — Smallest, 0.216 mm. long, 0.132 mm. broad between the ends 

 of the lateral horns, 0.104 mm. broad at the fundus, 0.06 mm. thick, with 

 the mouth 0.04 mm. by 0.028 mm.; largest, 0.26 mm. long, 0.164 mm. 

 broad at the ends of the lateral horns, 0.12 mm. broad at the fundus, 0.064 

 mm. thick, with the mouth 0.052 mm. by 0.028 mm. 



Locality. — Moderately frequent in the sphagnum of the cedar swamp 

 of Absecom, New Jersey. 



Nebela ansata, represented in figs. 1-8, pi. XXV, another remarkable 

 form, is distinguished by the spur-shaped appendages projecting from the 

 sides of the neck. It gives the impression of Nebela hippocrepis devoid 

 of the horseshoe-like body, which is the striking peculiarity of the latter. 

 The general shape of the shell is like that of N. hippocrepis, and it is also 

 about the same size. The lateral horns diverge upwardly at the conjunction 

 of the neck and body of the shell. They are hollow, acute, conical offsets 

 of the latter, and are usually more or less incurved, but are sometimes 

 nearly straight or slightly recurved. 



The structure of the shell is like that of the other species of Nebela, 

 and, like that of N collaris, presents great variety. Usually it is composed 

 of circular disks nearly uniform or of more or less variability in size. 

 Frequently the disks appear to overlap one another at the contiguous 

 borders, a condition also observed in the other species, though compara- 

 tively rarely. 



Occasionally specimens occur, as represented in fig. 1, in which a 

 number of partially detached disks are seen projecting along the inner mar- 

 gin of the lateral horns and on the opposite border of the body of the shell. 



The sarcode in all respects is like that in the previously described 



