THE GENERA OF MOSSES. 
465 
Of the first mentioned of these we have the genus Systy- 
liiim of HoRNsCHUCH, on account of the teeth being rather 
short, erect, geminating in pairs, and the hd connate with the 
columella. Of the second, we have the genus Cyrtodon of 
Brown, on account of the teeth being long and incurved 
at the apex. Of one of the last, Mr Brown observes, 
" Splaclmum Frodichianum et forsan aS*. Wulfenianum 
capsula inclinata et dentibus erectis a Splachnis genuinis 
distinguitur, et subgenus efformat.'' Under Aplodon, the 
same author shows, nevertheless, how near his Cyrtodon is 
allied to S. Frwlichianum : Diversa prsesertim dentibus 
erectis apicibus incurvis, ideoque S. Froelichiano dentibus 
erectis, sed geminatis affinis." Upon these principles, we 
fear, genera might be constituted of several more species 
of Splachnum ; for instance, Dissodon scahrisetum (Splach- 
num scahrisetum. Hook.) has the teeth involute in a re- 
markable degree, when moist -|-, and in this circumstance 
differing from all the rest ; this is, we apprehend, as valid a 
generic character as some of the above,— but, at the same 
time, of as little consequence. 
Of all the plants we have brought together under this 
genus, Systylium seems, at first sight, to have the greatest 
claims to be kept apart, and that, on account of the long 
persistent lid. We agree with Brown, however, that this 
can scarcely form a generic character. Under Aplodon, he 
observes, In hoc enim cohserentia operculi cum columella 
ex analogia cum Gymnostomis quibusdam, pro charactere 
specifici tantum valoris habenda sit " Besides, the lid even- 
tually separates from the columella : but a stronger reason 
* This plant is Orthotrichum Ludwigii. 
-f- We do not mean to say that the teeth were involute before the oper- 
cuium dropt off, but only after having been exposed to the action of the at- 
mosphere. 
VOL. V. G g 
