ON THE BEITISH SPECIES OF CRISIA. 181 



EXPLANATION OF PLATE XII, 



Illustrating Mr. Sidney F. Harmer^s paper " On the British 

 Species of Crisia/^ 



(AH the figures were drawn with a camera lucida under a Zeiss a objective, 

 and were subsequently reduced 2J diameters.) 



Fig. 1. — C. denticulata. — Young internode, with growing-point, seen 

 from the back (Canada balsam preparation). 



Fig. 2. — C. denticulata. — Illustrating the relations of an even-numbered 

 internode (pp. 147, 148). 



Fig. 3.— C. denticulata.— Ovicell (p. 169, &c.). 



Fig. 4.— C. aculeata.— Ovicell (p. 168, &c.). 



Fig. 5. — C. eburnea. — Abnormality (p. 158). 



Fig. 6. — C. eburnea. — Ovicell (p. 169, &c.). The internode which bears 

 the ovicell has two branches, an unusual arrangement. 



Fig. 7. — C. geniculata. — Internode with ovicell; back view (p. 172). 



Fig. 8. — C. geniculata. — Another ovicell, seen from the front (p. 172). 

 Greatest diameter of ovicell ^ "208 mm. 



Fig. 9.— C. cornuta.— Ovicell (p. 171). 



Fig. 10. — C. ramosa. — Ovicell broken open to show the valve (p. 170), 



Fig. 11. — C. ramosa. — Branch with ovicell (pp. 163, 168, &c.). 



Fig. 12. — C. ramosa. — " Suppressed" ovicell (p. 165). 



Fig. 13. — C. ramosa. — Internode which has abnormally developed four 

 ovicells (p. 166). 



