GENUS DIFFLUGIA— DIFFLUGIA CEATEKA. 109 



Later, October, 1878, in an additional supply of sediment, received 

 from Buffalo, in association with Geratium hngic'orne, I observed a number 

 of specimens of the same little Difflugia. 



The Bristol specimens of Difflugia cratera varied but slightly in any 

 respect. The shell, as represented in figs. 19, 20, pi. XII, was goblet- 

 shaped, with the body and neck of nearly equal length. The body, a little 

 longer than the neck, was ovoid, with the narrower pole forming the 

 fundus of the sheU. The neck was wide, cylindroid, and slightly ex- 

 panded approaching the mouth, which was large, circular, and terminal. 



The Buffalo specimens differed considerably from the former, as well 

 as among themselves, as seen in fig. 21, pi. XII, and fig. 35, pi. XVI. The 

 beautiful goblet-shaped shells varied in the proportionate length of the body 

 and neck. The former was more or less oblately spheroidal, and the 

 latter longer or shorter than the body, and expanded in variable degrees 

 approaching the mouth. 



In all the specimens, from both localities, the shell was composed of 

 colorless chitinoid membrane, which exhibited a minutely wrinkled appear- 

 ance, and sparsely scattered over the surface there were a few minute 

 sand grains and fine particles of dirt. 



The Bristol specimens measured about 0.056 mm. in length ; the Buf- 

 falo specimens ranged from 0.066 mm to 0.072 mm. in length. 



Since the above was written, it has occurred to me that the minute 

 shells, referred to Difflugia cratera, may perhaps pertain to a species of 

 ciliated infusorian, of the genus Tintinnus. 



DIFFLUGIA ACUMINATA. 



Plate XIII. 



Difflugia. Leclerc: M^m. Mus. Hist. Nat. ii, 1815, 474, pi. 17, fig. 5. 



Difflugia acuminata. Ehrenberg : Infusionsthierchen, 1838, 131, Taf. ix. Fig. iii. — ^Perty : Kennt. kleinst. 



Lebensformen, 1852, 187.— Leidy : Pr. Ac. Nat. Sc. 1874, 14, 79 ; 1877, 307. 

 Difflugia acuminata, var. acaulis. Perty : Ante, 187, Taf. ix, Fig. 6. 

 Difflugia bacillariarum. Perty : Ante, 187, Taf. ix. Fig. 7. 

 Difflugia pj/riformis. Carter: An. Mag. Nat. Hist, xii, 1863,251; xiii, 1864, 36, "acuminated variety," 



pi. i, fig. 1 1. 

 Difflugia proteiformis, var. acuminata. Wallich : An. Mag. Nat. Hist, xl, 1863, 453, pi. x, fig. 13. 



Difflugia f Carter : An. Mag. Nat. Hist, xii, 1864, 29, pi. i, fig. 10. 



Difflugia proteiformis, subspecies D. mitriformis, var. D. acuminata. Wallich: An. Mag. Nat. Hist, xiii, 



1864, 240, pi. xvi, figs. 11, 12. 

 D. Corticella acuminata. Ehrenberg : Abh. Ak. Wis. Berlin, 1871, 247. 



Shell amphgra-form or oblong oval, pyriform, or cylindroid with the 

 upper part more or less inflated ; fundus acute, acuminate, or prolonged 



