PLATE XVI. 



Figs. 1-24.— DIFFLUGIA GLOBULOSA. 



Figs. 1,2. Two views of au empty shell, composed of coarse quartz sand; fig. 1, inferior view 

 showing the circular month; tig. 2, lateral view. Ahsecom mill-pond. 200 diameters. 



Figs. 3, 4. Two. views of a large specimen, found with the preceding; magnified 100 diameters. 



Figs. 5, 6. Two views of a specimen with yellowish tint. Uinta Mountains, Wyoming. 200 

 diameters. 



Figs. 7, 8. Corresponding views of a living individual. Ditch below Philadelphia. 200 diameters. 



Figs. 9, 10. Similar views of a specimen, in which the shell is composed of chitinoid membrane 

 incorporated with narrow rectangular plates, etc., and the sarcode contracted into an encysted ball. 

 China Lake, Uintas, Wyoming, August, 1877. 200-f. 



Figs. 11,12. Inferior and lateral views of a small shell, composed of sand. Sphagnous swamp, 

 Ahsecom, N. J. 200 -f . 



Figs. 13, 14. Same, views of a small shell composed of chitinoid membrane incorporated with sand. 

 A continuous circle of sand grains surrounds the mouth. Sphagnous swamp. Broad Mountain, Pennsyl- 

 vania. 200-(-. 



Figs. 15, 1G, 17. Inferior, lateral, and superior views of a small shell composed of chitinoid mem- 

 brane with scattered sand grains. Pond near Cape May, N. J. 200-f-. 



FlGS. 18, 19. Lateral and inferior views oi a minute' shell, composed of chitinoid membrane, 

 striated and incorporated with scattered sand particles. An accumulation of the latter occupies the 

 fundus. Pokono Mountain, Pennsylvania. 500-f. 



Fig. 20. Interior view of a living individual, with shell of sand, and with colorless sarcode. 

 Fort Bridger, Wyoming Territory. 250 diameters. Shell of oval form 0.08 mm. long : 0.068 mm. broad. 



Fig.21. Inferior view of an empty shell, composed of chitinoid membrane incorporated with 

 large diatoms, etc. Sphagnous swamp, Ahsecom, N. J. A not unfreqnent kind. 500 -f . Shell 

 hemispheroidal, 0.030 mm. high; 0.058 mm. broad. 



Fig. 22. Similar view of a specimen composed of rectangular plates, together with a few diatoms. 

 Found with the preceding and likewise not an unfreqnent kind. Height, 0.032 mm. ; breadth, 0.054 mm. 



Fig. 23. Inferior view of an individual in which the shell was composed of brown chitinoid mem- 

 brane, incorporated with sand and dirt. Boggv place near Swarthmore, Delaware County, Pennsylvania. 

 500 4- . Shell 0.032 mm. high ; 0.05 mm. broad. 



Fig.21. Inferior view of a specimen in which the shell was composed of sand with intervening 

 brown cementing substance. Pseudopods numerous and more branching and pointed than usual. Same 

 locality as the preceding. 500-f. Shell 0.33 mm. high ; 0.05 mm. broad. 



Figs. 25-29.— DIFFLUGIA LOBOSTOMA. 



Figs. 25,26. Two views of an individual in which the shell appeared to be composed of yellowish, 

 cancellated chitinoid membrane as in the genus Nebela ; rig. 25, lateral view, with sarcode seen attached 

 by threads to the inside of the fundus of the shell. A large central nucleus and several contractile 

 vesicles situated at the periphery arc also visible. Fig. 20, inferior view exhibiting the trilobate moul b 

 and protruding pseudopods. Among Dnckmeat in a ditch below Philadelphia, June, 1874. 500 +. 



Figs. 27,28. Inferior and lateral views of a living individual, in which the shell was composed ot 

 colorless chitinoid membrane with a few scattered sand particles. Swarthmore brick-pond, May, 1874. 

 333 diameters. 



Fig. 29. Lateral view of a living specimen, in which the shell was composed of chitinoid mem- 

 brane with incorporated flocculent dirt, and in which the mouth was trilobed. Boggy place on Darby 

 Creek, Delaware County. 200-f-. 



Figs. 30, 31.— DIFFLUGIA ARCULA. 



Iuferior view of two empty shells of hemispheroidal shape, composed of yellow chitinoid mem- 

 brane incorporated with brownish dirt and a few scattered particles of sand. (The unsymmotrical 

 outline of fig. 30 correct, though probably accidental.) Sphagnous swamp of Atco, N. J. 250 diame- 

 ters. The shells shaped like that of an ordinary sea-urchin. Height of shell, 0.072 mm. ; breadth, 0.136 

 mm. to 0.14 mm. 



Figs. 32-34.— DIFFLUGIA UKCEOLATA. 



Fig. 32. Variety Difflugia olla. Lateral view of a living individual with protruded pseudopods. 

 Ahsecom pond, New jersey, October, 1875. 100-f-. 



Fig. 33. Egg-shaped variety, with a narrow projecting rim to the mouth. Lateral view of a 

 living specimen. A common form in a pond on Bridger Butte, near Fort Bridger, Wyoming Territory, 

 August. 1877. 250 diameters. 



Fig. 34. Variety Difflugia amphora. Lateral view with pseudopods extended. Common in the 

 ditches below Philadelphia, October, 1875. 100 diameters. 



Fig. 35.— DIFFLUGIA CRATERA. 



Lateral view of an empty shell composed of chitinoid membrane incorporated with fine sand par- 

 ticles. Lake Erie, Buffalo, N. Y., October, 1878. 500-f-. 



Fig. 36.— DIFFLUGIA .' 



Lateral view of an empty pyriform shell possessing two long divergent appendages, and c posed 



of colorless chitinoid membrane incorporated with irregular angular quartz particles. The onl\ speci- 

 men of the kind observed. Sphagnous swamp, Atco, N. 3. 25(i -(-. 



Figs. 37, 38.— DIFFLUGIA PYRIFORMIS. 



Fig. 37. Subpyriform variety approximating Difflugia glooutosa. Lateral view of a living speci- 

 men, the shell of which composed of angular quartz sand w it h a comparatively huge grain attached to 

 the fundus. Ditch below Philadelphia, March, 1875. 100-f. 



FlG. 38. Lateral view of an individual, from one side of the shell of which there projects unsvui- 

 metrically a comparatively large stone. Boggy place on 1 larbj I reek, 1 »hiw arc County, Pennsylvania. 

 100 diameters. 



Fig. 39. Nucleus pressed from an individual of Difflugia lohostoma, October, 1-74. 500 diameters. 



Figs. 40, 41. Isolated nucleus, and portion of crushed material from an individual of Difflugia 

 ureeolata. 500 diameters. 



