GENUS DIFFLUGIA— DIFFLUGIA PYHIFORMIS. 99 



Difflugia 1 Carter: An. Mag Nat, Hist, xiii, 1864, 29, pi. i, fig. 11. 



Difflugia proteiformis, subsp. D. mitriformis, var. D. pyriformis. Wallich: An. Mag. Nat, Hist, xiii, 1864, 



840. 

 Difflugia comprcssa. Carter: An. Mag. Nat. Hist, xiii, 1864, 22, pi. i, figs. 5, 6.— Leidy: Proc. Ac. Nat. 



Sc. 1874, 14 ; 1875, 307. 

 D. CortieeUa pyriformis. Ekrenberg: Abb. Ak. Wis. Berlin, 1871,247. 

 Difflugia entochloris. Leidy: Proc. Ac. Nat, Sc. 1874,79; 1875,307. 

 Difflugia vas. Leidy : Pr. Ac. Nat, Sc. 1874, 155 ; 1875, 307. 

 Difflugia nodosa, var. of pyriformis. Leidy : see following pages. 

 Difflugia cornuta, var. of pyriformis. Ibidem. 



Shell pyriform, flask-shaped, or ovoid, with the narrower pole prolonged 

 into a neck of variable length, of uniform transverse diameters, or more or 

 less compressed ; fundus obtusely rounded or subacute, or more or less ex- 

 panded and variably produced into from one to three conical processes; neck 

 gradually and evenly narrowed to the oral end, cylindroid, sometimes con- 

 stricted ; mouth inferior, terminal, circular, or slightly oval. Structure of 

 the shell usually of angular particles of quartz-sand, sometimes mingled 

 with diatoms ; less frequently composed of chitinoid membrane, with vari- 

 able proportions of diatoms and sand. Sarcode mostly with the endo- 

 sarc bright green, from the presence of chlorophyl grains, but often color- 

 less, except as modified by the presence of food. 



Size. — Ranging from 0.06 to 0.58 mm. long, 0.04 to 0.24 mm. broad ; 

 mouth 0.016 to 0.12 mm. wide. 



Locality. — Everywhere in the ooze of ponds, ditches, and bogs. 



Observed in Pennsylvania, New Jersey, Rhode Island, Connecticut, 

 Florida, Alabama, Nova Scotia, Colorado, Utah, Fort Bridger, and Uinta 

 Mountains, Wyoming. 



Variety 1. — D. pyriformis ; the ordinary characteristic form, with the 

 opposite diameters uniform. See pi. X. 



Variety 2. — B. compressa ; like the preceding, but more or less com- 

 pressed. See pi. XI, figs. 1-6; pi. XII, figs. 10-16. 



Variety 3. — D. nodosa ; usually a large form like the latter, but with 

 the fundus variably produced into from one to three eminences. 

 See pi. XI, figs. 7-22. 



Variety 4. — D. cornuta ; pyriform, with the fundus provided with one 

 or two pointed conical processes. See pi. XII, figs. 17, 18. 



Variety 5. — D. vas ; like the ordinary form, but with the neck defined 

 from the body by a constriction. See pi. XII, figs. 2-9. 



