PLATE XI. 



DIFFLUGIA PYRIFORMIS. 



The figures exhibit many variations in the also compressed variety, obtained, with multitudes of 

 the same kind, from Swarthmore brick-pond, Delaware County, Pennsylvania. Shells of clear angular 

 particles of quartz sand, with the bright-green endosarc visible through. The differences in the pseudo- 

 pods represent the appearances as actually observed. Magnified from 100 to 110 diameters. 



Fig. 1. Regular compressed pyriform individual. Length, 0.56 mm. ; greater breadth, 0.28mm. ; 

 less breadth, 0.18 mm. 



Figs. 2, 3. Two views of au individual ; the broader, unsymmetrical. 



Fig. 4. Broader lateral view of an individual in which the sareodo was contracted into a ball. 

 Breadth, 0.24 mm. by 0.16 mm. 



Fig. 5. Broader lateral view of au individual, with broad rounded fundus, of compressed pyri- 

 form shape. Breadth, 0.34 mm. by 0.18 mm. 



Fig. 6. Individual with prominent fundus. Breadth, 0.31 mm. by 0.16 mm. 



Fig. 7. Individual with conical fundus aud nipple-like summit. The green endosarc appeared 

 retracted to the fundus of the sarcode. 



Fig. 8. Transverse section and oral view of the same. 



Fig. 9. Broader lateral view of an individual with trilobed fundus. Breadth, 0.3 mm. by 0.16 mm. 



Fig. 10. Broader lateral view of a comparatively longspecimenwithnipple-likesummit. Breadth, 

 0.28 mm. by 0.16 mm. 



Fig. 11. Individual with broad trilobed fundus. The peculiar fan-like spreading of the pseudo- 

 pods was due to their extension beneath the inclined sidesof the cell in " Holman's life-slide." A quan- 

 tity of green corpuscles of the endosarc extended into the root of the pseudopods. Breadth of com- 

 pressed shell, 0.32 mm. by 0.18 mm. 



Figs. 12, 13. Two views of the same individual, the latter reversed longitudinally, exhibiting the 

 broader and narrower sides. 



Fig. 14. Individual with flat fundus, and with the sarcode contracted into a ball. Breadth 0.28 

 mm. by 0.16 mm. 



Fig. 15. Broader side view of a specimen with angular bilobed fundus. Breadth 0.26 mm. by 

 0.14 ram. 



Fig. 16. Broader side view of a specimen with rounded bilobed fundus. To the shell a conspicu- 

 ous crystal was attached. Breadth 0.32 mm. by 0.18 mm. 



Fig. 17. Broader side view of au unsymmetrical individual. The narrower side view was sym- 

 metrical and like that of the succeeding specimen. 



Figs. 18, 19. Two views of the same individual, the latter reversed, and appearing in the former, 

 with bilobed fundus. 



Fig. 20. Broader side view of an individual with conical fundus and lateral angular projections. 

 Breadth 0.28 mm. by 0.16 mm. 



Fig. 21. Broader side view of an individual with three blunt lobes to the fundus. Breadth 0.28 

 mm. by 0.16 ram. 



Fig. 22. Broader side view of an individual with quadrilobate fundus, unsymmetrical. A single 

 long pseudopod extended outwardly as it appeared in a. "Holman's life-slide." Breadth 0.32 by 0.16 mm. 



Fig. 23. Appearance of clear colorless corpuscles of the endosarc measuring from 0.00266 to 

 0.00798 mm. 



Fig. 24. Appearance of the green corpuscles having nearly the same range of size. 



