SECT. ii. CAERIGEEN. 23 



a mere film ; but it may be thin and flexible, thick, 

 tough, or leathery, according to circumstances. 



The Furcellaria fastigiata (fig. 23 B) has an inter- 

 mediate layer of cellular tissue between its skin, and a 

 pulpy interior. The frond is cylindrical, smooth, strong, 

 and opaque, repeatedly forked with long narrow forkings. 

 The root is fibrous, and the stem short and tapering. 

 Masses of spores nestle under the skin and swell out 

 the upper forkings, and oblong tetraspores are deeply 

 imbedded in the same. 



In the Dumontia filiformis the simple undivided stem 

 and branches are filled with a watery jelly. 



The stem of the Chylocladia kaliformis is a cylindri- 

 cal tube, from four to eighteen inches high, constricted 

 at intervals of half an inch or more into long hollow 

 joints; branches of the very same construction but 

 smaller spring from each constriction either opposite 

 to one another or in whorls ; these again have lesser 

 branches, all tapering more or less to each end. The 

 plant, which is of a pink colour fading to greenish 

 yellow, is propagated by tetraspores imbedded in the 

 branches, and by transparent conceptacles sessile on 

 the branchlets, enclosing nuclei containing pyramidal 

 spores. We neither possess the Constantinea rosa 

 marina, nor the C. sitchensis, some of the largest 

 and finest plants of the group, both being inhabi- 

 tants of high latitudes, but there are some very pretty 

 species on the British - coasts. They are supposed to 

 be annuals. 



The red dulses belong to the foliaceous and gelatinous 

 part of this order. The Chondrus crispus, or Irish moss, 

 sold as Carrigeen, is very common on rocky coasts in the 

 northern seas. It is from three to eight inches high, and 

 exceedingly varied in form. The frond is thickish, firm, 

 and elastic, with a stratum of cellular tissue under the 

 skin, which is probably much developed, as the plant 



