MARINE TANK. 103 



omorpha comprcssa. They arc found on almost all coasts, 

 at the very margin of high-water, and sometimes asso- 

 ciated with Ulva lactuca, Enlcromorpha inteslinalis and Bry- 

 opsis plumosa, which may be also introduced with safety 

 into a tank by a beginner. 



The Ulva latissima, or common green laver, or (as it is 

 also called) sea lettuce, which plant it much resembles, is 

 found very commonly at several points near New York. I 

 have observed fronds, full two feet in length by eighteen 

 inches wide, at Greenpoint, Long Island, though Lands- 

 borough gives, as its extreme length, eighteen inches. These 

 monsters would look well in a mammoth Aquarium ; 

 but, in our smaller tanks, fronds of from two to eight 

 inches in length are the best, They are always attached 

 to stones, which, as I have said, is the case with all 

 marine plants, though the ulva, as well as some few others, 

 will live detached and floating in our tank, but when so 

 situated, are not ornamental. They have no true root, 

 but derive all their sustenance through the surface of their 

 leaves, or, as they are called, "fro?ids." 



The Ulva latissima can be easily recognized from its resem- 

 blance to the common garden lettuce, and makes a very 

 pretty ornament for the Aquarium; from its bright green 

 color and the curiously puckered edge, it generally has 

 and would need no stronger recommendation to our notice, 

 even if it were not such a useful plant and such a good 

 aerator of the water. Specimens should be selected which 

 have not been attacked by snails and crabs, for the fronds 

 will soon assume a ragged aspect in an Aquarium where 

 whelks and soldier-crabs are kept with it. This particu- 



