168 On Bog Mosses. 



A question may arise, Whence the urticating power ? In the 

 hair alone, or some irritating substance within the hair? I am 

 inchned to the former, because hairs from cast skins kept for years, 

 and from cocoons two or three years okl, are equally urticating 

 with those from a living caterpillar, as are also the hairs mingled 

 with the webs spun by some of the sociable larvae. I look upon it 

 as a merely mechanical action, similar to that produced by the 

 hairs of the prickly pear, those from the interior of the fruit of 

 the wild rose or Cowhage, Doliclios urens, all of which are equally 

 productive of irritation, inflammation, and feverishness. 



To make out their structure caterpillar hairs should be mounted 

 dry, in fluid and in balsam. Anyone turning his attention to 

 them and not minding the risk of an occasional annoyance will be 

 well rewarded for his pains, and possibly wonder why more atten- 

 tion has not been paid by microscopists to so interesting and 

 instructive a class of objects. I can only account for the apparent 

 neglect on the ground that few entomologists work with the 

 microscope, and that microscopists generally have thought the hairs 

 of all caterpillars alike, whereas, as with the scales of the lepidoptera, 

 so with the hairs of their larvae, there is great variety of form and 

 markings. 



Finding so little said about them, and having moreover worked 

 at them for some years, I considered the subject of sufficient 

 interest to bring before the Society, with the hope that some 

 members may be induced to carry it further than I have done at 

 present, and to show to our lepidopterists that there is much in the 

 economy and philosophy of their branch of study worthy of being 

 critically examined. 



II.— On Bog Mosses. By E. Bkaithwaite, M.D., F.L.S. 



Plates LXXVI. and LXXVII. 



] 6. Sphagnum Lindbergii Schimper. 

 Torfmoose, p. 67, Tab. XXV. (1858). 



Plate LXXVI. 



Syu._ScHiMPER Synop. p. 679 (I860).— Linuberg Torfm. No. 2 (1862).— 

 IIartm. Skand. Fl. p. SI (1864).— Kvssow Torfin. p. 54 (1864).— Milde Bryol. 

 Siles. p. 389 (1869).— ArsTiN Muse. Appalacb. No. 40 (1870). 



Sph. cvspidatum /3 fulvum and Sph. /w/tum Sendtneb Mss. Sph. cuspidatnrn 

 LiNDBEKG in Bot. Notiser 1856, p. 122. 



Monoicous, in large dense tufts 6-12 in. high, glossy yellcuish 

 green, tinged uith ferruginous or purplish brown. Stem solid, dark 

 brown, with 3-4 cortical strata formed of irregular sizecl cells 

 withoid pores. Cauline leaves crowded, reflexed, broadly Ungulate, 

 auricled, the apex Inroad, truncate and fringed ; basal cells 

 hexagonal, in four rows, pale brown, tlien becoming narrow and 



