494 ULVACEAE. 



threads seem coarser than those of most Cyanophyeeae, but the microscope 

 shows that each thread is a cylindric bundle of closely compacted filaments of 

 the Rivularia or Calothrix type. Mangrove Bay (Hervey.) 



Sub-class CHLOROPHYCEAE. 



The affinities of the marine algae of Bermuda with those of southern . 

 Florida and the West Indian region are nowhere more clearly shown than 

 in the order Siphonales of the sub-class Chlorophyceae, more particularly in 

 such genera as Caulerpa, Avrainvillea, Udotea, Penicillus, Halimeda, 

 Codium, Valonia, Batophora, Dasycladus, Neomeris, Acicularia, and Ace- 

 tabulum, all of the species of which seem identical with those from farther 

 south. It is probable that systematic dredging operations in waters from 

 50 to 300 feet deep would materially increase the number of species of 

 Siphonales that Bermuda shares with Florida and the West Indies. Some 

 of the larger Green Algae that have been found are the following: 



Family ULVACEAE. 



Ulva Lactuca L., the Sea Lettuce, in various forms, is not uncommon, 

 especially in sheltered places. The thallus consists of a thin flat green mem- 

 brane, which is shown by the microscope to be two cells thick. 



The genus Monostroma, in which the thallus is outwardly rather similar 

 to that of the Sea Lettuce, but consists in the main part at least of only one 

 layer of cells, is represented by one or more species. 



The genus Enteromorpha, in most of the species of which the thallus is 

 tubular with the walls one cell thick, is represented by several species growing 

 in shallow water or on rocks or other objects between the tide lines. Entero- 

 morpha intestinalis tenuis Collins, E. flexuosa (Wulf.) Ag., E. fiexuosa 

 submarina Collins & Hervey, E. plumosa Kiitz., and E. minima Naeg. are the 

 names employed by Collins for the species issued in the Phycotheca Boreali- 

 Americana. E. plumosa Kiitz., the branches of which commonly terminate in 

 a single row of cells, has been found by Collins, attached to floating wood. 



Family VALONIACEAE. 



Valonia ventricosa J. Ag., Sea Bottles, one often finds washed ashore on 

 South Beach. The plant is essentially an ovoid, pyriform, or subglobose mem- 

 branous sac filled with protoplasm and attaining a diameter of one or two 

 inches. When living it is dark green and more or less iridescent. On being 

 killed and bleached it becomes beautifully pellucid and is as attractive then 

 as when living. 



Valonia macrophysa Kiitz. In this species the vesicles are smaller than 

 in the preceding and they often branch copiously, forming clumps as large as 

 a man's fist or even head. It occurs in shaded sheltered places, as in man- 

 grove swamps, and has an extraordinary development in the ponds near 

 Walsingham, where it forms large beautifully iridescent masses attached to 



