PLATE IX. 



Firs. 1-12.— OURAMCEBA VORAX. 



Fig. 1. Individual as seen moving -with the narrow end in advance, and with the tuftsof append- 

 ages trailing behind in a widely expanded manner. The interior so completely gorged with food, consist- 

 ing of algae, as to completely obscure the nucleus and contractile vesicle. The first specimen observed. 

 From a spring, in which grew water-cress, on Darby Creek, Delaware County, Pennsylvauia, May, 1874. 

 Magnified 200 diameters. 



Fig. 2. Individual from same gathering as seen in movement. Five tuftsof caudal filaments trail- 

 ing behind. A discoid nucleus seen in advance of the middle ; a contractile vesicle behind. The arrows 

 indicate the direction of motion of the three principal pseudopods. 



Fig. 3. The same specimen as observed in a contracted spheroidal form. 



Fig. 4. Specimen from a pond on Darby Creek, Delaware County, June, 1874. Provided with 

 only two tufts of short caudal filaments. The arrows indicate the direction of flow in the different 

 pseudopods. The nucleus and contractile vesicle distinctly seen. 250 diameters. 



Fig. 5. Specimen from same spring above mentioned, April, 1875. Body of palmate form, with 

 distinct nucleus and contractile vesicle. The caudal filaments widely divergent, and presenting irregu- 

 lar constrictions. The large diatom occupying an extension of the body to the left posteriorly was sub- 

 sequently withdrawn, and was finally seen to be expelled nearly in the same position it now occupies 

 in the figure; «., nucleus; p. v., contractile vesicle. 250 diameters. 



Fig. 6. Another specimen from same locality. Nucleus nearly central. 350 diameters. 



Figs. 7, 8. Two views of the same individual; a small specimen from the same gathering as that of 

 fig. 5. With a single pair of long caudal filaments. Nucleus unobserved. 350 diameters. 



Fig. 9. Another individual, with a pair of short caudal filaments projecting to the right of a mul- 

 berry-like process of the body. Nucleus just posterior to the middle. 350 diameters. 



Fig. 10. Two tufts of caudal filaments showing the mode of branching near their origin. 



Fig. II. A single detached tuft apparently starting from a button of somewhat consistent pro- 

 toplasm. 



Fig. 12. Portions of two filaments from the specimen of fig. 1, exhibiting the structure. Magni- 

 fied 400 diameters. 



Figs. 13-17. OURAMCEBA BOTULICAUDA. 



All the specimens from the spring above indicated. 



Fig. 13. Specimen obtained April, 1875. With three caudal appendages. A nucleus in advance 

 and two contractile vesicles behind. The latter came into contact, united in one, and then collapsed. 

 500 diameters. 



Fig. 14. Obtained January, 1878. Body somewhat palmate, containing a nucleus and two con- 

 tractile vesicles, and with four caudal appendages. 730 diameters. Body elongated to 0.0(5 mm., con- 

 tracted to 0.021 nun. 



Fig. 15. Specimen with three appendages, obtained May, 1874. 500 diameters. 



Fig. 16. Specimen with two tufts of appendages. From same gathering. 



Fig. 17. Specimen obtained with that of fig. 13. 



Five other specimens were observed at same time, all with three appendages except one, which 

 had nine appendages. One of the specimens was swallowed by a little worm, Chastogaster, and could 

 be distinctly seen within the stomach. 



