432 THE AUGUST HELEOPLANKTON OF NORTH WORCESTERSHIRE, 
divarieated, and the third antapical horn was rudimentary (fig. 17). I 
Observed the second form iniaetive movement. It progressed with the 
apieal horn forward, and its path was4peculiarly curved. 
I wish to thank the following gentlemen for kind permission to take 
collections of heleoplankton from the pools :— 
G. E. Wilson, Esq. 
+ + + 5. . Hureott and Podmore Pools, 
E. Phipps, Esq. 
+ + + + Broadwaters Pool, 
T. W. Biuyon, Esq... . , . Spring Grove Pools, 
Sir Chas. Holeroft . . Stanklin Pool, 
Stanley Baldwin, Esq. . . . . Wilden Pool, 
W. Westley, Esq. . . . ,. Island Pool, 
IZ. Hailes, Heq. . . , о, , Harvington Hall Moat ; 
and Г. Burcher, Esq., 
for information concerning the acreage of the pools. 
I wish also to thank Prof. G. S. West for continuous advice, suggestion, 
and criticism throughout the progress of the work, 
EXPLANATION OF THE PLATES. 
PLATE 34. 
Fig. 1. Microcystis ochracea, Portion of colony. X 730. 
Fig. 2, " » Outline of whole colony. x 66. The cells are confined 
within the dotted line, 
Fig. 3 Pteromonas aculeata. X 730. Normal form. 
Fig. 4. » » X 130. Axial view, showing rounded projections. 
Fig. 5. » » X 730. Slightly abnormal form: 
Fig. ( 7 
X Pteromonas ovalis, sp. п. x 730. 
Fig. 7. Scenedesmus Raciborski. X 730. Single colony, 
Fig. &. 5 n x 730. 
Five. 9 & 10. Oveystis parva. x 730, 
Fig. 11. Lagerheimia sp. X <0. Mother-cell with four daughter-cells, 
Fig. 12. " X 520. Single cell, 
Fig. 13. Crucigenia apiculata, x 730. Single colony. 
Fig. 14. Crucigenia reniformis, sp. п. x 730, Single colony. 
Fig. 15. Tetrastrum staurogenceforme. х 730. Single colony. 
Fig. 16. Ceratium Hirundinella. x 132, Form occuring in Stanklin Pool. 
Fig. 17. 
Single colony, viewed along axis. 
"n T x 132. Form occurring in Spring Grove Lower Pool, 
PLATE 35, 
MAP showing the lower portion of the Basin of the River Stour, Worcestershire. 
Pools from which heleoplankton collections were taken are named, 
