LEPTOGITTM. 157 



a little concave, or flat ; the disk reddish-brown, the paler mar- 

 gin entire. Spores ovoid-ellipsoid, muriform-multilocular (the 

 transverse (*) series ofspore-cells 4-8), soon decelerate, ^mic. 

 On moist clay, growing in patches of an inch at length in 

 diameter, and conspicuous by its light-blue colour. Illinois, 



Hall. Comparable in several respects with Pannaria byssina; 



but differs in the colour of the thallus, as in its strictly Colleme- 

 ine texture of mostly solitary or 2-3-concatenate gonimia (8-12 

 mic. diameter), nestling in pulp among anastomosing filaments ; 

 and in a distinguishable cortical layer. 



8. L. tenuissimum (Dicks.) Koerb.; thallus pulvinate, very 

 minute, lacero-laciniate ; from glaucescent passing into oliva- 

 ceous-brown ; the unequally linear, ascendant, acutish divisions 

 digitate - mul tifid j apothecia scattered, biatorine, small, to at 

 length almost middling-sized, adnate-sessile j the concave, red- 

 dish disk bordered by an entire margin. Spores ovoid- ellipsoid, 

 muriform-multilocular (the transverse series of spore-cells 4-8), 



soon decolorate, ^ mic. Dicks. PI. Cr. 1, p. 12, t. 2, /. 8, e 



descr.j & Auct. Angl., fide herb. Tayl. Koerb. Syst. p. 419, fide 

 Zw. exs. n. 173. L. lacerum minus, Auct. quorund. L. subtile, 

 Nyl. Scand. p. 34, fide ipsius. Tuckerm. Gen. p. 96. 



On sandy banks among mosses, and on dead wood, New 

 England (Wright; Willey), Tuckerman I. c. 1872. New Jersey, 

 Austin. Ohio, Lea. Illinois, Hall. British Columbia, Macoun. 



Islands of Behring's Straits, Wright. The fully developed 



lichen is commonly pale, but becomes brown, when it is now 

 much reduced, and the erect lobes take on a granulose look, 

 without any difference in internal structure. The name has 

 been much confused. The Leptogium subtile of Nyl. Syn. (in- 

 cluding not only L. tenuissimum, in part, but, according to this 

 author (Scand.) a small form of L. lacerum, as according to 

 Arnold (Fragm.) conditions also of L. minutissimum and L. 

 spongiosum) is admitted now, as emended (Scand.) by him, to 

 be the tenuissimum of Smith, as it is probably also of Dickson, 

 and certainly of Taylor. The lichen appears to be well sepa- 

 rated from both L. lacerum and L. minutissimum. 



9. L. minutissimum (Floerk., Seller.) Mass.; thallus micro- 



(*) ' Longitudinal' is now incorrectly used instead of transverse in 

 the author's Genera Licli. p. 96, etc. 



