PLATE XVI. 



Figs. 1-24.— DIFFLUGIA GLOBULOSA. 



Figs. 1,2! Two viewH of an empty shell, composed of coarae quartz sand; fig. 1,' inferior view 

 sliowins the circular mouth ; lig. 2, lateral view. Absecom 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, 187r. 200 +. 



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

 Absecom, N.J. 200 +. 



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

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

 vania. 200 -f . 



Figs. 15, 16, 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 +. 



Figs. 18, 19. Lateral and inferior views of a minute shell, composed of chitinoid membrane, 

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

 fundus. Pokono Mountain, Pennsylvania. 500 -f-. 



Fig. 20. Inferior 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, Absecom, N. J. A not unfrequent kind. ,'00 -f. Shell 

 hemispheroidal, 0.036 mm. high ; 0.058 mm. broad. 



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

 If'ound with the preceding and likewise not an unfrequent 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. Boggy place near Swarthmoro, Delaware County, Pennsylvania. 

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



Fig. 24. Inferior view of a specimen in which the shell was composed of sand with intervening 

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

 locality as the preceding. 500-(-. Shell 0.33 mm. high ; 0.05 ram. 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 : fig. 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 are also visible. Fig. 26, inferior view exhibiting the trilobate mouth 

 and protruding pseudopods. Among Duckmeat in a ditch below Philadelphia, June, 1874. 500 -f . 



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 floccnlent dirt, and in which the mouth was trilobed. Boggy place on Daiby 

 Creek, Delaware County. 200 -f . 



Figs. 30, 31.— DIFFLUGIA AECULA. 



Inferior 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 unsymmetrical 

 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 ram. ; breadth, 0.136 

 mm. to 0.14 mm. 



Figs. 32-34.— DIFFLUGIA URCEOLATA. 



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

 Absecom pond, New Jersey, October, 1875. 100 -|-. 



Fig. 33. Egg-shaped variety, with a, narrow jarojecting 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 Diffiugia amphoi-a. Lateral view with pseudopods extended. Common in the 

 ditches below Philadelphia, October, 1875. 100 diameters. 



Fig. 35.— DIFFLUGIA CKATERA. 



Lateral view of an empty shell composed of chitinoid niembram^ incmporated with fine sand par-' 

 tides. Lake Erie, Buffalo, N. Y., October, 1878. 500 -|-. 



Fig. 36.— DIFFLUGIA f 



Lateral view of an empty jiyriform shell possessing two long di veri;<'ut appendages, and composed 

 of colorless chitinoid membrane incorporated with irrogulai' angular quartz particles. The only speci- 

 men of the kind observed. Sphagnous swamp, Atco, N. J. 250 -|-. 



Figs. 37, 38.— DIFFLUGIA PYEIFORMIS. 



Fig. 37. Subpyriforui variety approximating Diffiugia gJohuJosa. L.atcral view of a living speci- 

 men, the shell of which composed of angular quartz sand with a comparatively large grain attaclied to 

 the fundus. Ditch below Philadelphia, March, 1875. 100 +. 



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

 metrically a comparatively large stone. Boggy place on Darby Creek, Delaware County, Pennsylvania. 

 100 diameters. 



Fig. 39. Nucleus pressed from an individual of Diffiugia lohonioma, October, 1674. 500 diameters. 



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

 urceolala. 500 diameters. 



