EUROPE AND NORTH AMERICA, 27 
4. Apex entire or indistinctly denticulate. 
S. molluscum, rubellum, cuspidatum. 
This, it will be seen, is readily applicable, but it has the dis- 
advantage of bringing together species not otherwise the least allied. 
Linpserc, in Ofvers. K. Vet. Ak. Foirhandl. for 1862, after 
separating S. macrophyllum as a genus Jsocladus, arranges the 
rest as follows :— 
1. Homophylla. Plants glossy, shining; hyaline cells quite 
free from spiral fibres. 
S. seviceum, Holleanum. 
2. Heterophylla. Plants opake; hyaline cells furnished with 
spiral fibres. 
A. S. cuspidata. 
S. cuspidatum, Lindbergit, recurvum, fimbriatum, 
acutifolium, teres, squarrosum. 
B. S. rigida. 
S. rigidum, Miillert, A. ngstromiit. 
C. S. subsecunda. 
S. subsecundum, rubellum, tenellum. 
D. S. cymbifolia. 
S. cymbtfolium. 
These groups are natural, have several characters in common, 
and are also adopted by Russow and Milde, except that they alter 
vigida to truncata, a more appropriate term, since it is applicable 
to all three species. 
I have also followed this arrangement, but at Professor Lind- 
berg’s suggestion have reversed the order, so as to commence with 
what we must consider the most highly developed species of the 
genus. 
ScHLIEPHACKE, in the paper already referred to, proceeds on 
the same plan, but increases the number of groups to seven, as 
follows :— 
I. acutifolia. 
S. rubellum, acutifolium, fimbriatum, Wulfianum. 
2. cuspidata. 
S. cuspidatum, laxifolium, Lindbergit.. 
3. squarrosa. 
S. teres, squarrosum. 
4. rigida. 
S. rigidum, Milleri, Angstrimii. 
