m
cohering in tooth-like fascicles. Cells very short. Striæ
strongly marlied.
Calothrix interrupta Carm. MS. C. interrupta Harv. in
Hook. Brit. Fl. p. ii. p. 368.; Harv. in Manual, p. 158.
ilab. On mosses and lichens, Appin : Capt. Carmichael.
Turk’s Cascade, Killarney ; and Tohermorey in the Isle
of Mull: W. II. Harvey. Machynlleth, N. Wales:
Air. Ralfs. Aberdeen : Dr. Dickie.
“ Filaments about a line in length, of a glaucous green
colour, united into close erect tufts, spreading over the moss,
thick, tapering, cohering at the base, and sometimes through
their Avhole length. Internal mass here and there interrupted,
leaving short pellucid spaces resembling articulations. Striæ
close and conspicuous.”— Carm. MS.
This species is certainly much more naturally placed in the
genus Stigonema than in Calothrix. Owing to the compactness
of the ceUs they do not exhibit the dotted or monili-
fonu arrangement of the other species — a difference surely
not generic. The colour is a light glaucous green.
5. Stigonema minutum Hass.
Plate L X V I I . Figs. 3, 4.
Char. Filaments minute, erect, rigid, flexuous, fastigiate.
Branches short. Cells or rather sporules in the principal
jiluments numerous, in the branches in single series.
Scytonema minutum Ag. S. minutum Harv. in Hook.
Brit. Fl. p. 365.; Harv. in Manual, p. 155.
Hah. On rocks and crustaceous lichens; common in alpine
districts, A p p in : Capt. Carmichael. Caroigataha
near Caher, and at Killarney : W. H. Harvey.
“ P lan t either spreading in a black suhorbicular crust or
scattered in little tufts, filaments erect, minute, closely packed,
olivaceous; branches irregular, obtuse, ascending.”—/fe re .
Not a very avcU marked species.
Char. “ Branches increasing by the elongation and division
o f a single cell.” — Berk.
The above definition, like tha t of Scytonema, embraces only
the essential character of the genus, to it, other well marked
peculiarities maybe added; such'as the rigidity of the filaments,
the branches usually solitary, and the beaded form of the cells.
The genus therefore may otherwise be defined th u s : —•
Char. Filaments somewhat rigid, o f unequal diameter.
Branches usually solitary, formed hy the elongation and
division o f a single cell. Cells distinctly moniliform, usually
in a single series.
Kiitzing’s genus Sirosyphon is thus specified: it includes
but a single species, and cannot be said to fulfil the intention
of the genus Hassallia.
“ Trichomata parenchymatica ex cellulis gelineis in vagina
lamellosa, apice clausa longitudinaliter striatis, apice in arti-
culos epenchymaticos confiuentes transeuntibus compositum.
Spermatia insterstitlalia. Rami basi geniculati.”
The above characters seem to me to be only of specific and
not generic importance.
The genus Hassallia was instituted by the Rev. Mr.
Berkeley a considerable time ago : that gentleman, however,
delayed publishing it, and conceived on the appearance of the
“ Phycologia Generalis” th a t it was frustrated by Kützing’s
genus Sirosyphon, which I cannot think that it is.
1. H assallia ocellata Hass.
Plate L X V I I . Figs. 2. 7. 6.
Char. Branches solitary, divaricating, slightly contracted at
the base. Cells beaded.
Conf. ocellata DiUw. t. d. Conf. ocellata E. B. t. 2530. ;
Harvey, in Hook. Brit. Fl. p. 364. Scytonema ocellatum
Harv. in Manual, p. 154.
Q 4