(82) 
Wahl. Synalissa, Fr. Phylliscum, Nyl.) the supposed Verrucariaceous 
structure of the fruit of which, re-asserted by Nylander, has procured 
general agreement to his distinction of this otherwise certainly marked 
lichen. As thus taken, the Omphalarie, with very few exceptions, are 
most readily recognizable in habit, but offer some discrepancies in their 
thalline structure, illustrating the intermediate and ill-definable position 
of the group, between Synalissa (itself, as here understood, not without 
similar discrepancies) and Collema. In the larger number of species, the 
gonimous system, represented by solitary or only clustered collogonidia, 
reverts in fact towards Synalissa ; and the assemblage thus indicated, 
as differenced from the inferior one preceding it by better developed 
medullary elements, and a foliaceous thallus, constitutes Omphalaria, Nyl. 
(Syn.): the few forms exhibiting concatenate collogonidia being by this 
author referred to Collema.' These discrepant types (Plectopsora, Mass.) 
are however, none the less evidently Omphalarieine, and essential there- 
fore to the completeness of our conception of the natural group of which 
they are members; in view of which, and of the little that is known of 
the value of the anatomical difference which distinguishes them, we may 
well follow Anziin declining to keep them apart. But there is still no 
doubt that, in placing Omphalaria cyathodes in close neighbourhood to 
Collema micrococcum, the learned author of the latest Synopsis Lichenum 
has but given expression to a genuine affinity. Ason the one hand, within 
the boundaries of the group before us, we all but touch Synalissa, 
so, on the other, the same group passes imperceptibly into Collema; 
every point of structural diversity at length failing, in the first direction, 
except the foliaceous thallus, and, in the second, except the peculiar 
attachment. These differences serve notwithstanding to define the 
assemblage. As Synalissa finds its nearest analogues in the reduced 
types of Pannaria, and the great mass of Collema and Leptogium in the 
frondose Pannarieé, and, more remotely, in Sticta and Nephroma, Ompha- 
1 To judge by the description and figure, Collema nummularium, Duf. (Nyl. 
Syn. p. 103, t. 4, f. 9) should be far more at home in Omphalaria; notwithstanding 
the structural reduction. Nor can I see sufficient reason for questioning the place 
of O. decipiens, Mass., which, alien in its gonimous elements to Collema, possesses 
much to make it comparable with Omphalaria pyrenoides, Nyl., and differs from 
all types of Pyrenopsis in its originally frondose thallus (specim. Arnold. in herb. 
Krempeth.! Koerb. Parerg. p. 431). Medullary filaments by no means wholly 
deficient in this lichen, as asserted by Nylander (Syn. p. 103) and by Koerber 
(l. ¢.). Compare, as to this, De Bary, Morph. § Phys. d. Pilze, Flechten, §c., p. 
266. A frondose type once admitted into Synalissa § Pyrenopsis, it might well 
appear less difficult, in view of Synalissa phylliscina, to restore Omphalaria phyl- 
lisca to the position assigned to it by Fries, —a position to which it is not without 
intrinsic claims ;—but this would be in effect to relegate, as a whole, Omphalaria 
to Synalissa, and doubtless the first step only to the re-establishment of Collema 
(exe. excip.) Ach. 
