16 



THUIDIUM PHILIBERTI Limpe., A NEW BEITISH MOSS. 

 By H. N. Dixon, M.A., F.L.S. 



In a note on Thuidium recognitum Lindb. in the recently pub- 

 lished Student's Handbook of British Mosses, p. 386, I referred to 

 Thuidium intermedium Phil. (= T. Philiberti Limpr.) as of doubtful 

 specific status, and probably equivalent to T. reco(jnitum. This 

 conclusion was based upon the full description of the plant by 

 Philibert in the Revue Brijolo(jique, 1893, p. 33, the only source of 

 information I then possessed. I have recently, however, received 

 from Dr. G. N. Best, of Eosemont, N3w Jersey, his Bevision of the 

 North American Thuidiums, and by the kindness of the same 

 bryologist an authentic fruiting specimen of the moss in question ; 

 and a study of the plant, together with the fresh light thrown upon 

 it by Dr. Best's description, has shown ^hat Philibert's account 

 is somewhat inadequate, and has induced me to alter my opinion 

 and to recognise in T. rhiliherti at least as good a right to specific 

 status as in the case of T. delicatulum Mitt, and T. recognition Lindb. 



Having once grasped the salient points of T. Philiberti, 1 had 

 little hesitation in referring to it a moss which I gathered on wet 

 rocks near the summit of Craig Chailleach, Perthshire, in 1893. 

 The plant, however, was without fruit, and bore only a few young 

 perichfetia, some of the more important distinguishing characters 

 being for this reason unavailable. I sent a specimen therefore to 

 Dr. Best, and his reply is as follows : — " Your Thuidium is indeed 

 T. Philiberti. I congratulate you on being the first to find it in 

 Scotland. Now that you know what it is, you will probably not be 

 long in finding it in England. It always grows in wet places, and 

 is usually sterile. As to its rank, I have to say that the more I 

 study it the more I am satisfied that it is a good species." 



As the moss has not been described in any of the systematic 

 works most in use, and the original description by Philibert is 

 difi'use and fails to point out or at any rate to lay stress upon some 

 of the leading characters (and in one point at least is slightly 

 inaccurate), I here subjoin Dr. Best's diagnosis of the species, 

 extracted from the Bulletin of the Torreg Bot. Club, xxiii. 84 (1896). 



Thuidium Philiberti Limpr. 

 Thuidium intermedium. Philib. Bev. Bryol. xx. 33 ; 1893. Not 

 Mitt. 1851. T. Philiberti Limpr. in Babenh. Krgptog. iv. 2, 835 ; 1895. 

 Medium-sized plants, yellow to dark green, in intricate mats ; stem 

 4-8 cm. long, creeping, pinnately branched ; branches pinnate or 

 bipinnate : paraphyllia multiform ; stem-leaves triaugular-cordate- 

 acuminate, usually with a hgaline jiliform. point, margins revolute 

 or recurved, at least below ; leaf-cells oblong-quadrate to oblong- 

 rhomboidal. Dioicous ; perichfetia! bracts loose, ftexuous spreading 

 or reflexed, serrate, rarely with a few short cilia on the innermost, 

 acumen about three times as long as the short, scarcely costate 

 body ; capsule oblong-cylindrical, curved, horizontal ; annulus 

 narrow, indistinct, tardily or imperfectly deciduous ; operculum 



