stratum of cellular tissue. Mixed with these are found numerous narrow, 

 elliptical, transversely striate bodies, which may be antheridia. The walls 

 of the frond are formed of several rows of hexagonal jointed longitudinal 

 filaments, combined together : the inner of which are of large size, with 

 long joints, the outer very minute and densely packed together. 



Few persons can visit the coast without becoming familiar 

 with this common plant, which is to be found in greater or less 

 perfection on all our shores. But it is in quiet land-locked bays, 

 with a sandy or somewhat muddy bottom, and in from three to 

 six fathoms water that it reaches its greatest size. In such places 

 it frequently forms extensive submarine meadows, so dense as 

 seriously to affect the passage of boats, and to endanger the life 

 of the unfortunate swimmer who may chance to become en- 

 tangled in its slimy cords, which when growing have conside- 

 rable tenacity. The smaller variety, which is by some authors 

 considered a distinct species, occurs between tide marks. Were 

 it of uniform size, and always distinguished by a denser and 

 brighter coloured covering of filaments, its rank might, perhaps, 

 be acknowledged; but I have found it impossible to fix its 

 limit in either character. It is connected by insensible grada- 

 tions with the common form. Some of the most distinct looking 

 individuals of this variety which I have seen, I owe to the kind- 

 ness of Mr. Ralfs, who procured them at Penzance. 



The fructification of this plant is more like that of the Lami- 

 nariece than of any Dictyotece, with the exception of the Antarctic 

 genus Adenocystis, which differs from Chorda more by habit than 

 any carpic character. Through C. Lomentaria, if that plant really 

 be a congener, there is a connection with Asperococcus, and so 

 with the other Bictyotem. Still I am inclined to think, notwith- 

 standing the different habit, that the present plant is properly a 

 member of the Laminaria group, in affinity as well as in habitat. 

 What I have called antheridia, which I find abundantly mixed 

 with the true spores, are perhaps what were first observed by the 

 late Capt. Carmichael, and are figured from his sketch in the 

 ' Flora Londinensis.' 



Fig. 1. Chorda filum, both varieties, young plants : — of the natural size. 

 2. A longitudinal semi-section of the frond. 3. The frond unrolled. 

 4. Transverse section of the wall of the frond. 5. Longitudinal section 

 of the same. 6. Spores. 7. Antheridia (?): — all more or less magnified. 



