(58) 



flabelliform manner; frequently the branches are more or less curved, and 

 the ramuli often secund. Structm-e : axis composed of longitudinal, arti- 

 culated, anastomosing filaments, occupying about one-half the diameter 

 of the frond, then becoming vertical, dichotomous, and at length simple, 

 moniliform, and highly coloured, parallel and densely-packed, forming the 

 surface. Substance externally rather firm, internally rather soft and 

 flaccid ; when young adhering more or less perfectly to paper. Colovir, 

 a dull brownish red, rather permanent. Tubercles lateral, near the 

 apices of the ramuli, mostly solitary, tm-ning the apex of the branch in 

 the opposite direction. Tetraspores we have not seen. 



The present pretty little species was at one period considered among 

 the rarest of British Algae ; and, although recent exploration has 

 detected numerous new habitats, and thus considerably extended its 

 range of distribution, it is still considered a scarce plant, and specimens 

 in good condition are by no means common in collections. Tetraspores 

 appear to be uncommon, as we have not seen them, but tubercles are 

 not unfrequent ; and we have been favoxxred with fine specimens in that 

 state by Miss Hodgson of Ulverstone. 



It may be distinguished from the last by its cylindrical stems and 

 branches, more straggling and more acute at the apices, frequently with 

 scarcely any distinct stem, less rigid in substance and rather brighter in 

 the colour. 



The external coating of these plants, especially of G. imtillata, is very 

 elastic, and when a transverse section of the frond is made and put in 

 water, the ring formed by the external coating of cells splits and rolls 

 backwards, forming a ring in its recurved position ; the vertical moni- 

 liform filaments that formerly lined its interior, now radiating from every 

 part of its surface, like the rays of light from a star, present a very beau- 

 tiful and curious appearance. The dermal coatings of several other Algse 

 are possessed of a similar property, but in some of them the action is 

 inwards not outwards ; and in some there is a strange tendency to twist 

 round in a spu'al, sometimes peculiarly annoying in microscopical exami- 

 nation, although very interesting to the curious, who are only in search 

 of striking objects for the microscope, and still more so to the philoso- 

 phical inquirer, to whom no form or development of animal or vegetable 

 life can present itself without a lesson of instruction. 



EXPLANATION OF PLATE LXXXIX. 



Fig. l.—Gigartina acicularis, natural size. 

 2. — Branchlet with tubercles. 

 3. — Section of tubercle. 

 4. — Spores. 



All magnified. 



