206 MR. G. H. WAILES ON FEESHWATER 



The tests figured by Leidy (figs. 24-27) have smaller and less divergent, 

 horns than those seen by me but are of about the same size, his figs. 28 and 

 29 are much larger (about 200 /x in length). 



This species is much smaller than either D. corona or T>. urceolata, has 

 fewer horns, and the circular aperture is devoid of any lip. The plasma 

 often contains zoochlorella cells. 



DiFFLUGiA LANGEOLAta, Penard. 



B. pyriformis pars, Leidy (6), p. 98, pi. 10. fig. 17. 



Occurs on the Palisades, IS .J., about 140 fju in length. 



DiFFLUGiA OLLiFORMis, Lagerlieim. (PL 15. fig. 12.) 



In Fcirli. Geol. Foren. Stockholm, xxiii. (1901) p. 512, figs. l-o. 



The test of this Diffiugia resembles that of D. suhcequalis, Penard (Revue 

 Suisse), but is rarely so large, is less truncate and much more variable in size. 

 The colour of the test is brown, with an aperture bordered by a collar usually 

 smooth but occasionally composed of small grains loosely aggregated. 



Length 80-87 yu. ; diameter 70-78 /i ; collar 36-42 /i. 



Distribution. — Carnegie Lake, Princeton, N.J. 



Li the 'Scottish Naturalist,' March 1912, p. 63, this species was recorded 

 doubtfully by me as D.suhcequalis. The limits of size in Great Britain are : — 

 length 50-84 /a, diameter 45-80 jx, collar 30-60 //,. A small variety about 

 30/1, in length also occurs in Yorkshire (Lagerheim, figs. 4 & 5). 



DiFFLUGiA URCEOLATA var. AMPHORA, Leidy. 



Leidy (6), pi. 14. figs. 8, 4, 8; pi. 16. fig. 34. 

 D. amphora, Leidy, Proc. Acad. Nat. Sci. Philad. 1874, p. 79. 



This variety is distinct from D. amphora, Penard (Faune Rhiz. Leman,. 

 1902), which is distinguished by a recess around the base of the neck, and 

 the collar having in side view a wavy outline, and by the expression of the 

 polygonal aperture. D. amplioralis, Hopkinson, is a much smaller species. 



Length 190-200 [jl (Leidy 200-600 yu,) ; diameter 125-128 /i ; aperture 58- 

 60 ytt. Similar to Leidy^s fig. 8, pi. 14. 



Distribution . — Yan Cortlandt Park, N.Y. 



Family Nebelina. 



Nebbla saccifera, sp. nov. (PL 15. figs. 7, 8, 9.) 



Diffiugia equicalceus pars, Leidy, Proc. Acad. Nat. Sci. Pliilad. 1874, p. 156, 



Nebela equicalceus pars, Leidy, ibid. 1876, p. 118, fig. 15. 



Nelela equicalceus, Wailes (16), p. 137. 



Nebela hippocrepis pars, Leidy (6), p. 156, pi. 24. fig. 13. 



Test of large size, pyriform, compressed, colourless, formed of circular 

 discs usually imbricated ; provided with two hollow curved horns, projecting 



