PLATE XIX. 



Figs. 1— -23.— DIFFLUGIA SPIRALIS. 



Figs. 1,2. Broader lateral, and anterior narrower views of tho same individual, with shell of 

 quartz sand and with extended pseudopods. Swarthmore brick-pond, September, 1874. 200 diameters. 



Fig. 3. Broader lateral view of a pair of individuals in conjugation. Ditch below Philadelphia. 

 September, 1875. 200 +. 



Fig. 4. Broader lateral view of a shell composed of rectangular plates, with diatoms, and cen- 

 trally with large angular particles of quartz sand. Hammonton pond, New Jersey, September, 1>77. 

 250 +. 



FlG. 5. Lateral view of an individual with extended pseudopods; the shell composed of quartz 

 sand, except contiguous to the mouth where it is formed of vermicular pellets. From ditch of a cran- 

 berry-bog, Atco, N. J., October, 1877. 250 -f . 



Fig. 6. Broader lateral view of a small specimen, with shell of quartz sand. Pool at Manayunk, 

 Philadelphia, 200 +. 



Fig. 7. Broader lateral view of an individual, with extended pseudopods, and shell entirely com- 

 posed of short vermicular pellets. A frequent kind in Absecom pond, October, 1874. 250 -}-• 



Fig. 8. Similar view of an individual, with a profusion of pseudopods. The shell composed as in 

 tho last, but with the vermicular pellets separated by narrow intervals, occupied with cementing sub- 

 stance. Found with the former, but only a few of the kind observed. 



Figs. 9, 10. Posterior and lateral views of a specimen in which the shell is composed of vermicular 

 pellets, as in fig. 7. Some of the pellets seen to project at the border. The interior contained an oval 

 brownish ball, probably the much reduced and contracted sarcode. Sphagnous swamp, Absecom, N. 

 J., March, 1875. 250 +. 



Fig. 11. Broader lateral view of an empty shell composed of vermicular pellets and a few large 

 particles of sand. Same locality, June, 1877. 250 -f. 



Fig. 12. Individual with shell apparently formed by a net with small angular meshes, and incor- 

 porated with a few large sand grains. Absecom pond, October, 1-74. 250 diameters. The structure as 

 represented I have suspected to be illusory, and to have been really as in fig. 8, but of this I am by no 

 means positive. I have seen no more of the kind since the above date. 



Fig. 13. Individual with shell of chitinoid membrane incorporated with scattered sand grains. 

 The outline of the sarcode mass is seen within, ending below in the projecting pseudopods. Absecom 

 pond. 225 -f . 



Figs. 14, 15. Broader side view of two individuals, with the shell composed of narrow rectangular 

 plates arranged in all directions and in close juxtaposition. The outline of the interior sarcode visible 

 with its extension to the mouth of the shell. Same locality. 250 +. 



FlG. 16. Small individual, with shell composed of chitinoid membrane incorporated with minuto 

 rods. It contains two balls : one oval and colorless, probably the sarcode; the other globular and 

 colored, probably discharged remains of food. Same locality. 250 -4-. 



Figs. 17, 18. Posterior and lateral views of an empty shell composed of chitinoid membrane incor- 

 porated with scattered diatoms. Sphagnum of Absecom, October, 1874. 250 +. 



Fig. 19. Broader lateral view id' a shell composed of chitinoid membrane, incorporated with scat- 

 tered rods, diatoms, and sand. Absecom pond. 250 -f-. 



Fig. 20. Specimen with shell composed as in the preceding, and containing four balls, of which, 

 the two colorless ones appeared to consist, of the sarcode, while the colored ones were supposed to con- 

 sist of discharged excrement, Found in company with the former. 250 -t-. 



Figs. 21,22. Posterior and lateral views of an empty shell, with unusually long neck, and com- 

 posed nearly as in the preceding specimens, with which it was obtained. 250 -f-. 



Fig. 23. Broader lateral view of a shell composed of elements of undetermined character. Abse- 

 com pond, June, lo77. 250 +. 



Figs. 24-2G.— DIFFLUGIA PYPJFORMIS. 



The shell of coarse quartz sand, and with a slanting constrictiou at the root of tho neck, so as to 

 give it an appearance approximating that of Difflugia spiralis. Swarthmore brick-pond, September, 

 1874. 200 -}-. Others of a similar character found at the same time. Sarcode colorless, except a 

 clay-colored hue to the eudosarc. Most specimens also exhibited a black patch, probably due to some 

 peculiar food. 



Figs. 27-29.— DIFFLUGIA UKCKOLATA. 



Fig. 27. Small individual, with shell id' chitinoid membrane incorporated with diatoms and sand, 

 and wilb an unusually irregular surface. China Lake, Uinta Mountains, Wyoming Territory, August, 

 1877. 250 +. 



Fig. 28. Variety Difflugia olla. Lateral view, with shell composed of coarso sand, and with pro- 

 jected pseudopods. Absecom pond, New Jersey. 200 -f-. 



FlG. 29. Variety Difflugia olla. Lateral view of an empty shell, composed of chitinoid membrane, 

 incorporated with diatoms, etc. Found in the same locality as the preceding. V00 -(-. 



