AMBLYSTEGIUM COMPACTUM IN BRITAIN 177 
seaxnia the two, and was led to conclude that A. densum ide 0% 
B uratz. must be held to be simply synonyms of 4. 
a fee t. 
Not possessing at that time any authentic specimens of the 
North American plant, I felt some Fig Hv in accepting this posi- 
tion, and ventured to point out to Dr. Cardot some of the apparently 
important distinctions between the two plants as gamete the one 
by American, the other by European writers. In reply, Dr. Cardot 
obligingly sent me specimens from all the 4. So . he pos- 
sessed from North America (including A. subcompactum C. & 
Kindb. and a. dissitifolium Kindb.), and upon examination of these 
I could not doubt for an instant the identity of these plants with 
the European plants which I had seen that have passed under 
the various names of B, denswm, A. cryptarum, &¢. (see synonymy, 
given below). 
There remained, however, several points to be cleared up, and 
it will be most convenient to tabulate the chief differences that 
taken tt Pale given by Milde : and Limpricht. in addition 
p 
sBecese of the authorities at sap of ape. the type specimen, 
in Hooker’s Herb., of H. compactum C.M d this has materially 
aided me in forming the seas pees 
A. compactum. B, densum. 
As ps section. Martie strand 1. Central strand obsolete or 
small, 3 to 6 in diameter, of wanting. Cortical cells thick- 
4 to ie rows of oie all tissues walled. 
mang, thin walls. 
2. Brood-filaments, Not de- 2. Nerve of leaf frequently 
scribed. producing hyaline or orange- 
rown rhizoid filaments from 
the ba 3 
8. Inflorescence. Autoicous. 8. Dioicous. Male flowers and 
} sit unknown 
4, Perichatial bracts, os . With short nerve. 
narrow, percurrent or excu 
itat. On decayed erat calcareous rocks, in 
5. On 
at the bases of via in swamps caves and hollows of walls. 
or ee stream 
Stem section. This is clearly a character subject to variation 
ies to the degree of development of the part chosen he 
description by Cheney doubtless refers to the strongest and most 
highly oe sa s, and between these and the smaller — 
which the tral ani is often quite wanting, are no 
doubt all disse oe development. Thus, in a fairly da adi dary 
stem of A. compactum (Madison, Wisconsin, leg. Cheney and True), 
