THE NIADES OF MISSOURI 181 
shows stomata with companion cells and the adjoining cells of the epidermis. 
Fig. 8. Section of chlorenchyma in cotyledon. (IS) Intercellular 
space. (Cl) Chlorenchyma proper. 
Fig. 9. Cross section of a cotyledon. (Ep) Upper epidermis, (EP) 
Lower epidermis, (Hy) Hypodermis, (Cl) Chlorenchyma, (Xy) Xylem, 
(Ph) Phloem. 
Fig. 10. Cross section of epicotyl. (Ep) Epidermis, (Hy) Hypodermis, 
(Pa) Parenchyman, (Ph) Phloem, (Ca) Cambian layer, (Xy) Xylem, (Pi) 
Pith. 
Fig. 11. Cross section of the petiole of one of the first leaves. (Ep) 
Epidermis, (Hy) Hypodermis, (Pa) Parenchyma, (Xy) Xylem, (Ph) Phloem. 
Fig. 12. Cross section of an early leaf. (Ep) Upper epidermis, (Ep) 
Lower Epidermis, (CI) Chlorenchyma, (Is) Intercellular Space, (St) Sotma, 
(Xy) Xylem, (Ph) Phloem. . 
Fig. 13. An advanced stage of seedling growth. 
THE NAIADES OF MISSOURI.—III. 
BY WILLIAM I. UTTERBACK. \ 
Rotundaria granifera (Lea). 
(“Purple Warty Back,’ “Purple Pit.”) 
PLO REN, Rags 55 A and. 
1838— Unto grantferus Lea, Tr. Am. Phil. Soc., Vi, p. 69, Pl. XIX, fig. 60. 
1900b—Quadrula granifera (Lea) Simpson, Proc. U. S. Nat. Mus., 
SX. 705. 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Identical with those of R. tuber- 
culaia in all respects. 
REPRODUCTIVE STRUCTURES:—Typical specimens from the 
Mississippi show the outer gills marsupial; conglutinates same 
color and form as those of R. tuberculata; glochidium measures 
0.290 X 0.350mm., being a little larger with more of an undulated 
hinge line, but with the same general form. 
SHELL CHARACTERS 
EXTERNAL STRUCTURES:—Like R. tuberculata except smaller 
rotund, upright, alated, inflated,—especially fuller, higher, more 
antero-protruding beaks and with more of a rayed character of 
epidermis on anterior umbonal slope. Interior of shell identical 
