132 



SEAWEEDS 



The Geographical Distribution is general, and the 

 best-known British marine forms are V. dichotoma, 

 V. synandra, V. Thureti, V. sphcerospora, and V. 

 litorea. 



CODIACE^E. 



General Characters. The order is represented by 

 the genera Codium and Bryopsis, differing in habit and 

 mode of branching, but agreeing in the production 



a 



FIG. 35. Codium tomentosum. a, part of section showing club-shaped cells 

 of periphery with lateral sporangia highly magnified ; b, one such cell with 

 sporangium more highly magnified. 



of gametes of two sorts, between which conjugation, 

 though it has not been observed, may yet be pre- 

 sumed with much probability to occur. Derbesia, also 

 included here, is of more simple vegetative develop- 

 ment, and possesses, so far as is known, but one kind 



