156 FEESH WATER RETIZOPODS OF NOETH AMEEICA. 



Nebela collaris. It is colorless, except that the endosarc is more or less 

 brownish or yellowish, from the usual abundance of food-balls and dif- 

 fused material of the same nature. 



I have also observed N. carinata with the sarcode mass in an encysted 

 condition and the shell closed with an epiphragm. A specimen of this kind 

 is represented in fig. 5. 



NEBELA HIPPOCREPIS. 



Plate XXV, figs. 9-14. 



Difflugia (Nebela) cqvicalceus. Leidy : Proc. Ac. Nat. Sc. 1874, 156. 

 Nebela equicahciis. Leidy: Proc. Ac. Nat. Sc. 1876, 118, fig. 12. 



Shell compressed pyriform, witli a thick, blunt, solid carina extending 

 around the body at the fundus and lateral borders, and ending in long 

 digitate processes projecting downward into the interior of the cavity. 

 Mouth transversely oval, convex downward. Shell transparent, colorless, 

 composed of circular disks; the carina pale straw-colored, homogeneous, 

 indistinctly granular. Sarcode, in color, structure, and arrangement, as in 

 N collaris and N. carinata. 



Size. — Length 0.252 mm. to 0.26 mm.; breadth, including carina, 

 0.14 mm. to 0. 16 mm.; thickness 0.068 mm. to 0.072 mm., with the 

 mouth 0.04 mm. by 0.028 mm., and the carina 0.016 mm. deep and 0.008 

 mm. thick. 



Locality. — Wet sphagnum at the borders of Absecom pond, New- 

 Jersey. 



Nebela hippocrepis, a remarkable species, represented in figs. 9-14, 

 pi. XXV, is related to Nebela carinata, which it resembles in shape, but is 

 larger. It is rare, as I have observed but six specimens in four years, 

 and these were found only in the wet sphagnum at the edge of Absecom 

 pond, New Jersey. 



The shell is compressed pyriform and variable in the proportions of 

 breadth to length, and a longer specimen may be of less breadth than a 

 shorter one. 



The top of the fundus and lateral borders of the body of the shell are 

 occupied by a thick horseshoe-like keel, the ends of which project down- 



