( 36 ) 
as interpreted by those of Peltigera, are also, through the latter, associa- 
ble in a manner with those of Sticta. Nor is this all. Fries remarked of 
the fruit of Sticta aurata (ZL. E. p. 51) in itself not seldom comparable with 
that of Nephroma, that it agreed essentially with that of Cetruria; and 
it is with the genus last named that we may well compare the one before 
us. We do not indeed find in Nephroma the same satisfactory evidence 
of an originally closed thalline exciple, as is afforded by Peltigera; but 
the young, connivent apothecium is far from unlike that of Cetraria, 
which may also be taken to explain the mostly obscure margin. There is 
scarcely any difference apparent between apothecia of Nephroma tomen- 
tosum and others of Cetraria lacunosa, so closely approximated are the 
points of attachment in the two, though in the one case the fruit really 
adheres to the underside of the thallus, and in the other to the upper; 
and in the Himalayan C. Stracheyi, Babingt. (Hook. f. et Thoms. Herb. 
Ind. Or. n. 2080) even this distinction disappears, and the apothecium is 
quite like that of Nephroma in every important, external respect. C. cil- 
iaris also is occasionally comparable with Nephroma in the same way as 
C. lacunosa; and Sprengel’s Peltigera (Nephroma) Americana (Syst. Veg. 
4,1, p. 306) is only, as appears by his original specimen, a condition of the 
first-named. Indeed, we need look no further than the genus in hand to 
demonstrate its true affinity. Ina fine specimen of Nephroma antarcticum 
before me, almost every one of the dozen and more apothecia is distinctly 
enclosed by a regular, entire margin, the Parmeliaceous character of 
which is quite beyond question. 
It is another curious circumstance that Cetraria, though so well dis- 
tinguished by its cartilagineous thallus, and other features pointing to a 
different affinity, yet agrees with Nephroma in offering indications of 
cyphelle; these occurring both in C. Stracheyi, just mentioned, and in 
C. leucostigma, Lév. (Sticta Wallichiana, Tayl.) from the same region 
(Herb. Hook.) the scattered shields of which last well simulate those of 
Sticta. The cyphelle (properly the modification known as pseudo-cyphell@) 
of Nephroma tomentoswm point, we need scarcely add, as obviously toward 
Sticta, as do other characters toward Peltigera; and the genus must con- 
tinue to be regarded as mediating between the other two. 
About twelve species are described, their range being northern (that 
of the finest, alpine and arctic) and austral. Of the European forms all 
but one occur here.——WN. levigatum, Ach., the smooth condition of what 
Acharius described as N. parile (Tuckerm. Syn. N. Eng. p. 18) and dis- 
tinguishable from N. tomentoswm (Hoffm.) Koerb., which is N. resupina- 
tum, Ach. a (Tuckerm. 1. ¢., & Exs. n. 13, pr. parte) by its smooth and 
naked under side, is common in the New-England mountains; and occurs 
also, rarely, with an at length bright-yellow medullary layer (California, 
Mr. Bolander) upon which compare Nylander 1. c. p. 320, note. 
