56 MARINE 



E. lanceolata. Formerly called Ulva Lima. Frond narrow, ribbon- 

 like, six to twelve inches long, one inch to two inches wide ; blunt or 

 pointed at apex, tapering at base ; attached by a disk ; edges much 

 ruffled; bright green, soft, thin. 



GENUS Monostrotna 



This genus resembles Ulva, but is more delicate since it has 

 but one layer of cells, as its name implies. The frond is usually 

 sac-like at first, then breaks apart, leaving a thin, semi-trans- 

 parent membrane of no definite shape. 



GROUP SIPHONED 



The distinct and peculiar character of this group is that in each 

 individual the whole plant consists of but one cell. There are 

 many genera, some of which are plants of elaborate form and 

 considerable size, but always the one cell expands and branches 

 without dividing the elongated cavity with septa, or plates of 

 division. In Caulerpa the stability of the plant is secured by 

 numerous fibrils which emanate from the interior of the cell, 

 forming a spongy network of interlacing filaments. In other 

 orders the branches gain support from incrustation, from inter- 

 lacing, and from cohering on the edges. 



ORDER VALONIACEJE 



The algae of this order are found only in tropical or subtropical 

 waters. Their holdfasts resemble fibrous roots and penetrate the 

 sand or coral on which they grow. 



GENUS Chamcedoris 



C. annulata. When young this alga consists of an annulated tube 

 formed of a single cell. The annular constrictions occur at short inter- 

 vals, giving it the appearance of being jointed. It grows to the height 

 of two to three inches, when it ceases to lengthen and produces a dense 

 mass of filaments, forming a head or spherical tuft one inch or more in 

 diameter. It is bright grass-green in color, rather rigid and tough, and 

 when mature is thinly coated with carbonate of lime. The holdfast is a 

 tuft of fibers. The species is found at Key West and is a native of the 

 West Indies. 



