Botanical Society of London. 295 



mannia new to the British Flora : Jungermannia reclusa (MSS. Tay- 

 lor), J.fragilifolia (MSS. Taylor), /. germana (MSS. Taylor), and 

 J. riparia (MSS. Taylor). 



Read " Observations on some varieties of Hypna and on a new 

 species of Lichen," by Dr. Thomas Taylor. 



Local collections of Cryptogamic plants are instructive in two 

 ways ; by contributing to our knowledge of the geographical distri- 

 bution of the species, and by pointing out the directions which the 

 Characters of the varieties take when acted on by diversity of cir- 

 cumstances of external agencies. The Cryptogamic collection of 

 Dr. G. Watson from the vicinity of Philadelphia, presented to the 

 Botanical Society of London, elucidates in some particulars the fore- 

 going remark ; not however to a great extent, as the collector seems 

 to have satisfied himself with gathering the largest and most promi- 

 nent species, and to have omitted or overlooked the minuter and 

 more inconspicuous kinds : yet what has been collected is far from 

 being destitute of interest and value. 



Thus he has remitted to London a great profusion of Neckera cla- 

 dorrhizans (Hedw.). Now this moss was first described from Swiss 

 specimens by Hedwig ; it was afterwards sent to this country from 

 Nepal by Dr. Wallich, and from New York by Dr. Torrey ; finally 

 we have it in the present collection from Philadelphia. 



In Great Britain and Ireland, so fertile in mosses, it is totally un- 

 known. We may therefore conclude that this species is altogether 

 continental, although for the present we are unacquainted with those 

 laws that deny to it an insular locality. 



We have Hypnum salebrosum (llo&m.),hY its smaller size, imposing 

 upon us the form of a new species ; but although the branches are 

 more compressed and shorter, the leaves somewhat narrower, the 

 pedicels more slender, and the capsules soon turning black, yet in 

 all essential characters it entirely agrees with our British species. 



Hypnum plumo sum (L.) with us assumes diversified forms, among 

 which a remarkable one, collected by the late Miss Hutchins at Glen- 

 geriff^, has all the leaves decidedly secund. 



The variety gathered by Dr. Watson has the upper leaves alone 

 heteromallous ; but then its more erect and longer capsules, and the 

 less concave but substriated leaves, claim the adjustment of the ba- 

 lance between species and variety by a practised hand. 



Dr. Taylor considered it less hazardous for the present to leave it 

 in the rank of the latter. But the impatient may say, when then are 

 we to expect the means of exactly deciding ? The answer is, perhaps, 

 not until some muscologist enjoys the privilege of seeing both grow- 

 ing in their native localities ; for there is much value in the cha- 

 racter taken from the habit of a plant. Many modern elevations of 

 varieties to the rank of species have been first suggested by the 

 silent appeal of the look of the growing individuals. 



In Dr. Watson's state of Hypnum rutabulum (L.), a mark hitherto 

 considered essential to the species seems to be vanishing. The 

 pedicels exhibit scarcely any appearance of roughness immediately 

 below the capsules ; in all other particulars the Philadelphian and 



