reniform, gland-like processes oblique, solitary at the end of
each margin. Gelatinous sbeath evident. Zygospore spherical,
smooth, placed between the empty segments, the filament previous
to conjugation breaking up into single joints.
S iz e . Diam. 12-14 p (W.) ; 22-S3 p (K.) ; 25-35 p (R.).
Zygospore 21
Rabh. Alg._ Eur. (1868), iii., 148. De Bary Conj. t. 4, f.
82-34. Brebisson Liste Desm. (1856), p. 119. Archer in
Prit. Inf. (1861), p. 24, t. 1, f. 15-17, Cleve Sver. Desm.
(1864), p. 496. Lundell Desm. Suec. (1871), p. 91. Petit
Liste Desm. Paris (1877), p. 29. Wolle Desm. U.S. (1884),
t. 4, f. 18. Wittrock Scan. Desm. (1869), p. 25. Jacobsen
Desm. Denm. (1874), p. 211. Kirchner Alg. Schles. (1878),
p. 133.
Odontella ? unidentata, Ehr. Infus. (1838), p. 159.
Istlmia verteirata, Meneg. Syn. Desm. (1840), p. 205.
Istlmosira vertehrata, Kutz. Phy. Germ. (1845), p. 141.
Sphcerozosma unidentatum, Ralfs. Ann. N, H. d8451 xvi t
3, f. 7. ■
Sphoerozosma elegans, Corda Aim. Carls. (1835), t, 4, f. 37.
Hassall Pr. Alg. p. 348, t. 84, f. 1.
H ab. In ditches.
Cornwall, Sussex, Kent, Westmoreland, Norfolk ; France,
Germany, Italy, Sweden, Denmark, United States.
Plate I I ., Jig. 1. a, living cells ; I, empty cells ; c, side view ; d, transverse
view ; e f, zygospores.
S p hæ ro z o sm a e x c a v a tum . Malfs. Desm. 67, t. 6 ,/. 2.
Joints longer than broad, subquadrate, very minute, constriction
a deep rounded sinus on both sides, and two sessile glandlike
projections on each margin at their junction ; angles
sometimes with three very minute teeth ; no evident gelatinous
sheath. Zygospore elliptic, placed between the empty joints
the filament previously breaking up. ’
S iz e . Diam. 9-12 p (W.) ; 8-12 p (K.) ; 10 x 18 u (R.).
Rabh. Alg. Eur. (1868), iii., 29. Wolle Desm. U.S. (1884),
t. 4, f. 8-12. Brebisson Liste Desm. (1856), p. 119. Archer
in Prit. Inf. (1861), p. 724. Nordstedt Desm. Arct. (1875)
p. 15. Cleve Sver. Desm. (1864), p. 469. Lundell Desm!
Suec. (1871), p. 92. Nordstedt Norges Desm. (1873), p. 47
Petit Liste Desm. Paris (1877), p. 29. Wood P. Water ÀUæ
U.S. (1872), p. 123. Wittrook Scan. Desm. (1869) p. 25
Notaris Desm. Ital. (1867), p. 29, t. 1, f. 5. Wil’le Nov!
Sem. (1879), p. 62. Nordstedt Desm. Spitz. (1872), p 26
Jacobsen Desm. Denm. (1874), p. 211. Kirchner Alo- Schles’
(1878), p. 183.
Isthmosira excavata, Kutz. Phyc, Germ. (1845), p. 141.
Schistochilum excavatum, Ralfs. Flor. Tunbr. Wells (1845),
p. 192.
H ab. In pools.
Cornwall, Sussex, Kent, Surrey, Hants, Westmoreland, Lancashire,
Gloucester ; France, Spitzbergen, Germany, Denmark,
Norway, Sweden, Nova Zembla, United States.
Plate I I ., fig. 2. a, living cells ; b, transverse view ; e, empty cells ;
d, empty cells further magnified ; e, zygospore.
S p hæ ro zo sm a filifo rm e - (Ehr,) Rahh, Alg. Eur, III., 149.
Joints about as long as broad ; constriction acute ; segments
elliptic, and united by double slender processes, which include a
quadrate foramen between each pair.
S i z e . Diam. 1 2 - 1 8 p (W.) ; 1 2 - 1 4 p (K.).
Wolle Desm. U.S. ( 1 8 8 4 ) , t. 4 , f. 5 , 6 . Archer in Prit. Inf.
( 1 8 6 1 ) , p. 7 2 4 . Archer Mior. Journ. ( 1 8 6 9 ) , p. 1 9 7 . Lundell
Desm. Sueo. ( 1 8 7 1 ) , p. 9 1 . Jacobsen Desm. Denm. ( 1 8 7 4 ) ,
p. 2 1 2 . Kirchner Alg. Schles. ( 1 8 7 8 ) , p. 1 3 3 .
Tessarthra fiUformis, Ehr. Inf. 1 5 4 , t. 1 0 , f. 2 1 .
Isthmosira filiformis, Kutz. Phyc. Germ. ( 1 8 4 5 ) , p. 1 4 1 .
H ab. In pools.
Ireland, Germany, Sweden.
Plate I I ., fig. 6. a, living cells ; b c, empty cells.
S p hæ zo zo sm a p y gm æ um . PabTi. Alg. Bur. HI., 160.
Filament minute, joints a little broader than long, even,
acutely notched, segments about twice as broad as long, almost
elliptical, constriction a linear, acute notch ; end view sub-
elliptic. Enclosed in a narrow hyaline sheath.
S i z e . 8 x 8 p ( 0 . ) .
Cooke in Grevillea ix., 3 9 .
H ab. In pools. Barmouth, N. Wales.
Plate I I ., Jig. 5. a b, living cells ; c, empty cells ; d, empty cells X
1000.
** Filaments destitute of a mucous sheath, isthmus obsolete.
Sp hæzozosma s e c e d e n s . De Bary Conj. 67, t, 4,,fi. 35-37.
Filament very fragile ; joints as long as broad ; constriction
a shallow rounded sinus ; segments subelliptio, ends concave ;
no gelatinous sheath.
S i z e . 1 2 x 1 0 p ( 0 . ) .
Rabh. Alg. Eur. ( 1 8 6 8 ) , iii., 1 5 0 . Archer Micr. Journ.
( 1 8 7 1 ) , p. 9 2 .