PLATE XVI. 



Figs. 1-24.— DIFFLUGIA GLOBULOSA. 



Figs. 1,2. Two views of .til empty shell, composed of coarse quartz sand; tip,'. 1, inferior view 

 showing flie cirenlar month ; fig. 2, lateral view. Alisecom mill-pond. 200 diameters. 



Figs.3,4. Two views of a large specimen, fonud with (be preceding; magnified 100 diameters. 



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

 diameters. 



Figs. 7, 8. ( lorresponding views of a living individual. Ditch below Phfladelpbia. 2C0 diameters. 



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

 incorporated with narrow rectangular plates, etc., and the Barcode contracted into an encysted hall. 

 China Lake, Uintas, Wyoming, August, I s ??. 200-f-. 



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

 Absecom, N. J. 200-f-. 



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

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

 vania. 'JIO-J-. 



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

 brane will) scattered sand grains. Pond near Cape May, X. J, 2'ltl-f-. 



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

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

 fundus. Pokono Mouutain, Pennsylvania. .00+. 



Fig. -0. Inferior view of a living individual, with shell of sand, and with colorless sarcode. 

 Fort Bridger, Wyoming Territory. 260 diameters, shell of oval form 0.08 mm. long; 0.OJ8 mm. broad. 



Fig. b1. Inferior view of an empty shell, composed of chitinoid membrane incorporal ed with 

 large diatoms, etc. Sphagnous swamp, Alisecom, N. J. A not unfrequent kind. LOO -f-. Shell 

 hemispheroidal, ::> una. high ; 0.058 mm. broad. 



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

 Found w ii h the preceding and likewise' not an unfrequent kind. Height , 0.032 mm. : Ore acllh. 0.0.4 mm. 



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

 brane incorporated with sand and din. Boggy place near Swarthmore, Delaware County, Pennsylvania. 

 £00-)-. 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 -|-. Shell 0.33 mm. high ; 0.05 mm. broad. 



FIGS. 25-:9.— DIFFLUGIA LOBOSTOMA. 



FlGS. 25, 25. Two views of an individual in which the shell appeared to he composed of yellowish, 

 cancellated chitinoid membrane as in tin- genus Nebela : fig. 25, lateral view, with sarcode seen attached 

 by thre ds to the inside of die fundus ot the shell. A large central nucleus and several contrac ile 

 vesicles situated at the periphery are also visible. Fig.2 ; . inferior view exhibiting the trilobate mouth 

 ami protruding pseudopods. Among Duckmeat in a ditch below Philadelphia, June, 1874. 500 -(-. 



Figs. 'Si , '.s. Inferior ami lateral views * « 1' a living individual, in w hie h the shell was composed ot 

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

 333 diameters. 



FlG. 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. 



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 unsymmefrical 

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

 ters. The shedls shaped like that of an ordinary seu-urchin. Height of shell, 0.072 mm. ; breadth, 0.13(3 

 mm. to 0.11 linn. 



Figs. 32-34.— DIFFLUGIA UECEOLATA. 



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

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



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

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

 August, 1877. 250 diameters. 



lie;. :',!. Variety Difflugia amphora. Lateral view with pseudopods extended. Common in the 

 ditches below Philadelphia, October, 1875. 100 diameters. 



Fig. 35.— DIFFLUGIA CEATEEA. 



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

 lie lis. Lake Erie, Buffalo, N. Y., October, 1*?8. 500+. 



Fig. 33.— DIFFLUGIA ? 



Lateral \ iew of an empty pyriform shell possessing two long divergent appendages, and composed 

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

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



Figs. 37, 38.— DIFFLUGIA PYE1FOEMIS. 



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

 men. Hi.' shell of win. h composed of angular quartz sand w ith a comparatively large grain attached to 

 tin- fundus. Ditch below Philadelphia, March, 1875. 100+. 



Fig. 33. Lateral view of an individual, from one' side of the shell of which there- projects unsym- 

 motricall,\ a comparatively large stone. Boggy place' on Darby Creek, Delaware County, Pennsylvania. 

 100 diameters. 



Fig. 39. Nucleus pressed from an individual of Difflugia lobostoma, October, 1874. ECO diameters. 



FlGS. 40, 41. Isolated nucleus, and portion of crushed material from an individual of Jjifflugia 

 urceolaia. ;"i"' diameters. 



