159 



the Correspondence of Linnaeus, &c.' ii. 433, proves that this great 

 botanist considered the two forms to be species. — " In Scania I have 

 met with the flowers, male as well as female, of both species of Ca- 

 lamistrum, figured by Dillenius, in his Historia Muscorum, by the 

 name of Calamaria.'''' 



Gray, in his * Natural AiTangement of British Plants,' makes two 

 varieties in addition to the normal form of the plant, and describes 

 them as follows. 



/3. gracilis. Leaves long, slender. 



Calamaria folio longiore et graciliore. Dill. M. 541. 

 y. fragilis. Leaves very brittle, slender, pointed, transparent, pores numerous, 

 minute. 



Subularia fragilis, folio longiore et tenuiore. Raii Syn. 307. 3. 



By a reference to Ray* it will be seen that this Subularia fragilis is an 

 addition by Dillenius, and is doubtless identical with the Calamaria 

 folio longiore &c. of that author ; the forms are thus again reduced to 

 two, and concerning these Mr. Wilson, who has paid great attention 

 to the subject, kindly sends me his opinion in the following words. 



" The solitary plants with short spreading leaves, I believe to be the 

 first fiill development after the seedling state, and before any lateral 

 extension of the rhizoma has taken place : when the plants are crowd- 

 ed together, either by lateral increase (or offsets) or by a multitude of 

 individuals in close contact, the fironds can grow only in an erect pos- 

 ture. In a specimen from Llyn Ogwen, the tallest I have, and which 

 I cut through the middle before drying, the section of the rhizoma or 

 tuber is very large, while in another specimen, gathered in the same 

 place, and at the same time, the rhizoma is very small and inconspi- 

 cuous ; in a third specimen the rhizoma is very broad and concave at 

 the base. The size of the tuber may depend on the age and vigour 

 of the plant ; its analogy with the rhizoma of ferns I think consider- 

 able : when a number of the outer or lower fironds have ripened and 

 dropped off, then and not before it becomes exposed to view." 



Mr. Sansom has given the two supposed species a minute and care- 

 ful examination, and has favoured me with the following remarks. — 

 " In the diffuse variety the seeds are globular or nearly so, and the su- 

 tures in many cases very indistinct, while in the erect plant the seeds 

 are angular, the angles appearing to be formed by the swelling of the 

 edges of the sutures, and thus giving it an angular appearance. Again, 

 the texture of the seed is different ; in the diffuse plant it has a slight- 

 ly pellucid appearance, while, in the erect variety, they are of a firmer 



* Syn. Ed. 3, p. 307. 



