PLATE X. 



DIFFLUGIA PYEIFORMIS. 



The shells of most specimens represented, and the same may be said of the other species of Diffln 

 gia represented in the succeeding plates, are composed of irregular angular particles of quartz sand, 

 ■which particles are mostly drawn only in outline. The transverse diameters of the specimens are uni- 

 form except in cases specially indicated. 



Fig. 1. Individual with pseudopods protruded; the endosarc bright green. Swarthmore brick- 

 pond, May, 1874. 200 diameters. 



Fig. 2. Individual from the same gathering. The Barcode contracted into a ball, the endosarc 

 of which was bright-green. 200 -)-. 



Fig. 3. Individual with profuse extension of pseudopods; the sarcode colorless; the shell of 

 coarse sand grains. Pond on Darby Creek, Delaware County, Pennsylvania, May, 1874. 100 diameters. 

 Fig. 4. Large individual with profusion of pseudopods; endosarc colored apparently only from 

 the presence of food. Shell comparatively even. Absecom pond, New Jersey, June, 1674. 133 diame- 

 ters. The same gathering contained many like it, ranging from 0.32 to 0.. r > mm. in length. 



Figs. 5,6. Two specimens; in the one with bright green endosarc; in the other with the endosarc 

 colored brownish centrally. Ditches below Philadelphia, June, H74. 200 diameters. 



Figs. 7-12. Individuals from Absecom pond, New Jersey, June, 1674. In all except the last one 

 green coloring matter was absent in the endosarc. 200 diameters. Specimens collected in the same 

 locality the following September and November presented the same appearances. Fig. 7. An unsym- 

 metrical specimen. The shells presented various degrees of unevenness and proportionate size. 



Fig. 13. Individual with remarkably uneven shell, composed of coarse sand and a large diatom 

 case. Endosarc centrally brownish. Cranberry-swamp, at Atco, N. J- , April 1877. 200 +. 



Fig. 14. Specimen with shell of uuusually coarse sand. An abundant variety from a sphagnous 

 bog on Budd's Lake, Morris County, New Jersey, November, 1874. 250 diameters. The same kind 

 observed in material from a sphagnous bog of Absecom, New Jersey, April, 1675. 



Fig. 15. Large shell, slightly unsymmetrical, composed mainly of irregular angular quartz sand, 

 but with a few rounded ones (which is very unusual), and a sponge spicule. Empty specimen. 200 

 diameters. Similar ones from 0.05 to 0.58 in length occasionally found. 



Fig. 16. Large form, with shell of coarse sand, common in China Lake, Uinta Mountains, Wyo- 

 ming Territory, August, 1877. 250 diameters. Specimens varying from 0.2 to 0.36 mm. in length, with 

 shell of coarse sand, and endosarc centrally bright green. 



Fig. 17. Empty shell, composed of comparatively thin angular flakes of quartz. A not unfre- 

 quent variety. Hammonton pond, New Jersey, July, 1877. 500 diameters. 



Fig. 18. Empty shell, composed of narrow rectangular plates, diatom cases, and a comparatively 

 few sand grains. From sphagnum bordering a spring at Swarthmore, Delav. are I lounty, Pennsylvania,. 

 250 diameters. 



Fig. 10. Specimen with shell composed of sand, diatoms, and spongilla spicules; the sarcode con- 

 tracted into a ball, and colorless. Absecom pond, New Jersey, November, 1*75. 1.'.;'. diameters. 



Fig. 20. A similar specimen from same gathering, with shell of sand and diatoms, and sarcode 

 coiorless. 100 diameters. Large specimens like this and the former, mostly with shell of variable pro- 

 portions of sand and diatoms, and with colorless sarcode, are not unfrequent in the ponds of sphagnous 

 bogs of New Jersey. 



Fig. 21. Individual with shell of rectangular plates and a few coarse sand grains, and with sar- 

 code contracted into a ball. Sphagnous bog of Absecom, New Jersey, November, 1875. 260 diameters. 

 Fig. 22. Small form, with shell composed of clear chitinoid membrane, incorporated with diatoms, 

 sand, and dirt, and with yellowish endosarc. Pond near Egg Harbor, New Jersey, September, 1875. 

 500 diameters. 



Fig. 23. Empty shell of chitinoid membrane incorporated with large diatoms and dirt. Found 

 with the last. The same form, living, occasionally found in sphagnous bogs of New Jersey. 



Figs. 24, 25. Forms occasionally observed in water of the cedar swamp of Absecom, New Jersey. 

 Shell of yellowish chitinoid membrane with incorporated diatoms, sand, and dirt. Sarcode colorless 

 or with brown endosarc. In the individual of fig. 25 it formed an oval, brown encysted ball. 



Fig. 26. Individual with shell of chitinoid membrane incorporated with thin siliceous plates, and 

 with sarcode attached to the fundus of the shell by long pseudopodal threads. Absecom pond, Now 

 Jersey. 



Fig. 27. Individual with Bhell of black dirt. Absecom pond, New Jersey, October, 1874. 200 

 diameters. 



