Fresh water. Pentland Hills, Dr. Grerille. Near Silverdale, Lancashire,
Dec. 1855, Mr. Johnson.
This interesting form was first collected by Dr. Greville in the above locality,
and is well distinguished from all the other species of this genus by its coarser
moniliform striæ and cuneate ends.
Supp. Plate LXII. 389.
G e n u s 52. D IC K IE IA , Ralfs.
Frond membranous, leaf-like; frustules imperfectly siliceous, scattered,
naviculoid, oblong ; valves elliptical, striated.
This genus is easily distinguished from the last, from which it
differs in the character of its frond, as well as the structure of its
frustules. Nor is it likely to be confounded with any subsequent
genus, its flat leaf-like form, and the irregular and scattered arrangement
of the imbedded frustules being peculiar.
1. Dickieia ulvoides, Ralfs. Frond entire, linear, or obovate, with
a distinct pedicel; valves elliptical; nodule more or less stauri-
form ; striæ 36 in -OOI". Length of frond -3" to 1'4". Breadth of
frond '06" t o ’d". Length of frustule ‘OOIO" to '0013". v.s.
Berk, and Ralfs, Ann. ser. 1. vol. 14. pl. ix. Prit. Anim. xxiv. 31. Kiitz.
Bacill. p. 119 ; Sp. Alg. p. 109.
Marine. Near Aberdeen, April 1844, Dr. Dickie.
Plate LIV. 342.
2. Dickieia pinnata, Ralfs. Frond irregularly divided; divisions
rudely pinnate or laciniated ; valves elliptical-lanceolate ; nodule
punctate. Length of frond -3" to l-l" . Breadth of frond -l" to
•6" ; striæ 40 in -001". Length of frustule '0009" to -0011". v.s.
Ralfs, Ann. ser. 2. vol. 8. pl. v. 6.
Marine. Near Aberdeen, Sept. 1851, Dr. Dickie. Cumbrae, March 1853,
Mr. Hennedy ; commimicated by Dr. Arnott.
Plate LIV. 343.
G e n u s 53. B E R K E L E Y A , Grev.
Frond gelatinous, definite, tuberculate at base, emitting towards its
circumference filaments enclosing the densely-packed frustules;
frustules naviculoid; valves linear-lanceolate, obtuse.
1. Berkeleya fragilis, Grev.
to -6". Length of frustule
•0003". v.v.
Striæ obscure. Length of frond •2"
•0015" to -0035". Breadth of valve
Grev. S. C. F. tab.294. Grev. B. F. p .416. Balfs, Ann. 1 ser. vol. 16. pl. iii. 2.
Kiitz. Bacill. p. 109 ; Sp.Alg. p. 96. Berkeleya Adriatica, Kiitz. Bacill.
xxii. 4 ; Sp. Alg. p. 96. ad spec, authen. quæ misit am. De Brebisson.
Prit. Anim. xvii. 34 & 35.
Marine. Torbay, Mrs. Griffiths. Cumbrae, Sept. 1853, Mr. Hennedy,
and Oct. 1854, Dr. Arnott. Cork Harbour, Oct. 1855, W. Sm. (Cherbourg,
M. De Brébisson. Montredon near Marseilles, May 1854, W. Sm.)
The tuberculate character of the frond in the present genus seems to arise
from the adherence of the gelatinous filaments towards their bases, and is
more or less distinct at different stages of the plant’s growth. In an advanced
state the adherence is less conspicuous, and the entire frond becomes filamentous.
The two species given by Kützing have apparently owed their
determination to this circumstance, as I can find nothing in the structure or
character of the frustules to warrant the separation of B. Adriatica from
our native form. The genus is sufficiently distinguished from its allies by
the form, arrangement and structure of its frustules, which cannot be confounded
with those of the filamentous species afterwards to be described.
The valves are striated, as is evident from their colour, which is a very pale
straw ; hut I have not been able to resolve the striæ so as to ascertain their
number.
Plate LIV. 344.
G e n u s 54. ENC YO NEM A, Kütz.
Frond filamentous, tubular, sparingly divided ; frustules cymbelloid ;
valves convex, striated ; striæ moniliform.
The frustules of the present genus so closely resemble those of
Cymbella, that a superficial observer would fail to detect their true
character in a prepared gathering. A careful inspection would, how