ON THE BEITISH SPECIES OP OEISIA. 163 



EXPLANATION OF PLATE XI, 



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

 Species of Crisia." 



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

 and were subsequently reduced 24 diameters.) 



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

 from the back (Canada balsam preparation). 



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

 internode (pp. 129, 130). 



Fig. 3.— C. denticulata.— Ovicell (p. 151, &c.). 



Fig. 4.— C. aculeata. — Ovicell (p. 150, &c.). 



Fig. 5. — C. eburnea. — Abnormality (p. 140). 



Fie. 6.— C. eburnea. — Ovicell (p. 151, &c.). The internode which bears 

 the ovicell has two branches, an unusual arrangement. 



YiG. 7. — C. geniculata. — Internode with ovicell; back view (p. 154). 



Fig. 8. — C. geniculata. — Another ovicell, seen from the front (p. 154). 

 Greatest diameter of ovicell = '208 mm. 



Fig. 9. — C. cornut a.— Ovicell (p. 153). 



Fig. 10. — C. ramosa. — Ovicell broken open to show the valve (p. 152), 



Fig. 11.— C. ramosa.— Branch with ovicell (pp. 145, 150, &c.). 



Fig. 12.— C. ramosa. — " Suppressed" ovicell (p. 147). 



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

 ovicells (p. 148). 



