184 DR. S. O. LINDBERG ON MESOTUS. 
posal, I feel unable to decide whether this curious dimorphism of 
the spores is normal or a deformity); all of them are globoso- 
tetrahedral, but the larger sometimes oval. The calyptra was 
absent in all the specimens. 
This interesting moss has the habit of Macromitrium, Brid. 
Mant. Musc. p. 132 (1819), in Orthotrichee; the form of the 
leaves is like that in Holomitrium, Brid. Bry. Univ. i. p. 226, 
no. 21 (1826), in Dicranee; but the form of the perichetial 
bracts resembles the leaves of Symblepharis, Mont. Ann. Se. 
Nat. ser. 2, viii. p. 252 (1837), among Ditrichee (Leptotriches). 
The structure and areolation of the bracts agrees well with that 
of Macrodon, W. Arn. in Mém. Soc. d' Hist. Nat. Paris, ii. p. 299, 
n. 45, 1825 (Walkeria, Hornsch. in Flora, viii. pt. 2, Ergánz. 
p. 21, 1825; Leucoloma, Brid. Bry. Univ. ii. p. 218, n. 97, 1827), 
a link of Dicranee vere. 
According to this structure of the leaf, 7. e. the distinct brown 
alar cells, the minute areole of the parenchyma, with strongly 
inerassate walls, and very small nearly stellate lumen, and warts 
on both sides, as also the distinet border at the margin, I think 
Mesotus, Mitt., must be placed among Dicranee vere, near to 
Macrodon, W. Arn., in which group it forms a link analogous 
to Desmotheca, Lind. (Cryptocarpus, D. M. Musc. frond. Arch. 
Ind. p. 5, 1844, and Muse. frond. ined. Arch. Ind. fasc. ii. p. 37, 
t. 15, 1845; but, in Chenopodiacee, there is already a Crypto- 
carpus, H., B., K. Nov. Gen. Sp. Amer. ii. p. 187, tt. 123 & 124, 
1817), of Orthotrichee. About the male inflorescence I can say 
nothing, as I have not been able to find any andrecium; pro- 
bably the plant is dicecious. 
In speaking of the cells, I have used the term warts; and 
perhaps it will not be out of place to glance at the asperities on 
the cells of Mosses and Liverworts, as they are often of great use in 
systematic arrangement. We have, 1 think, the following three 
principal forms of asperity, of which the first two are occasioned 
by the prominence of the cell-wall itself, the last by excrescences 
from the cuticle only. 
1. Cellule pulvinate—when the wall of the cell is, on one or 
both of its free sides, regularly round-convex, as in Rhabdo- 
weissia striata, and very many Hepatice. 
2. Cellule papillose —when the wall of the cell is, on one or both 
of its free sides, conically prominent, either at the middle of the wall 
or at one or both ends, as in Bartramiee and Lejeunia echinata, Sc. 
