82 



CHLOROPHYCEAE 



Fig. 56. Neomeris. A, plants of N. annulata ( x ^). B, young plant of N. 

 dumetosa ( x j). C, longitudinal section through apex of N. dumetosa ( x J). 

 D, rhizoid in N, dumetosa ( x J). E, transverse section of thallus of N. dumetosa 

 in middle of calcified area ( x ^). F, A'', dumetosa, assimilating filaments with 

 sporangium ( x ^). G, A^. annulata, sporangium ( x 33). H, regeneration of an 

 injured axis ( x j). (A, G, after Taylor; rest after Church.) 



*Dasycladaceae : Acetahularia (acetabular little cup ; aria, derived 

 from). Fig. 57. 



This is a lime-encrusted genus which is confined to warm waters, 

 extending up as far as the Mediterranean in the northern hemi- 

 sphere. The plants consist of an erect elongate axis bearing one or 

 more whorls of branched sterile laterals with a single fertile whorl 

 at the apex. The sterile whorl or whorls are frequently shed in the 

 adult plant leaving a mark or annulus on the stem to show where 

 they were formerly attached. The fertile whorl is composed of a 

 series of long sac-like sporangia which are commonly fused, 

 though they are sometimes separate : these are borne on short basal 



