LKPTOOIUM.] 



COLLEMEI. 



67 



8. L. cretaceum Xyl. Act. Liim. Soc. Bord. ser. 3, i. (1857) 

 p. 270 ; Syn. i. p. 120. — Thallus rosulato-lobulate or stcUato-laci- 

 niate, olive-brown or dark-olive ; the lobes unequal, crenate, almost 

 imbricate. Apothecia small, nearly biatorine, concave or gyalecti- 

 form, pale reddish-browu, the margin entire, paler ; spores ovoid, 

 .*3-7-septate, with longitudinal septa, 0,022-40 mm. long, 0,011- 

 17 mm. thick. — Mudd, ilan. p. 45 : Cromb. Lich. Ui'it. p. 7 ; Leight. 

 Lich. Fl. p. 32, ed. 3, p. 27. — Eachi/liuia cretaceum Gray, Xat. Arr. 

 i. p. 398. Collema creUweum Sm. Eng. Fl. v. p. 210. Lichen 

 cretaceus Eng. Bot. (1800) t. 738. 



This plant appears at first as minute, very thin, olive or dark stellee, 

 somewhat imm n-sed and distinct. These become more prominent, ap- 

 proximate and contiuent, till it attains the perfect state. It is occasionally 

 seen in an isidiomorphous condition. The gonimia are rarely monUiform. 

 The apothecia, seen only in the best developed specimens, are small in 

 the scattered, and moderate in the confluent rosidce. 



Hah. On cretaceous and siliceous nodules in moist shady places in 

 upland tracts. — Distr. Confined to the Chalk and Oolite districts of S. 

 and W. England ; probably in its yomig state often overlooked. —B. M. : 

 Near Folkestone, Kent; Plumpton and West Dean, Sussex; Reigate 

 Hill, Surrey ; Isle of Wight ; Brighton Downs, Sussex ; near Xorthleach, 

 Gloucestershire; Stokesay, Shropshire. 



ft. <;■ 



^fA 



9. L. microscopiciim Nyl. BuU. Soc. 

 Bot. Fr. iv. (1857) p. 920; Syn. i. 

 p. 122, t. 4. f. 17.— Thallus effuse, very 

 minute, fruticulose, erect, branched, 

 olive-brown, dark-brown or blackish ; 

 branches slender, elongato-papillate, un- 

 equally rounded, somewhat constricted 

 or attenuate at the base. Apothecia 

 very minute, scattered, concave, pale 

 brown or brownish-red, the margin 

 smooth, entire ; spores ovoid or oblong, 

 3-5-septate, and murali-locular, 0,022- 

 27 mm. long, 0,009-14 mm. thick. — 

 Cromb. Journ. Bot. 1874, p. 336 ; 

 Leight. Lich. Fl. Suppl. p. 468, ed. 3, 

 p. 34. — Brit. Exs. : Cromb. n. 7. 



In its earher stages of growth this has 

 the appearance of a Sirosophon. The thal- 

 lus is cellular, and the gonimia are often 

 J3-moniliform. Though resembling a mi- 

 nute state of L. lophceum, it is distin- 

 guished by its peculiar habit aud the Fig. 17. 

 form of the spores. It is very rarely Lcptorjium microscopicum Nvl. 

 fertile. On the thallus is occasionally —«. Thallus, x 30. b. Sec- 

 seen a parasitic Ohryzum described here- tion of apothecium, x30. 

 after. c. Three spores, X 500. 



Hob. On slaty rocks, but chiefly on chalk pebbles and calcareous walls, 



f2 



