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Transactions of the Society. 
specimens from many places ; one example from Adel, W. Yorks., 
was quite oblong. (Long, sine papill. 75 y ; lat. s. papill. 40 y.) 
Genus Cosmarium Corda; Ealfs. 
14. C. canaliculatum sp. n. PL IV. fig. 57. 
C. mediocre, circiter l j-plo longius qnam latius, profucde 
constrictum, sinu angusto-lineari, extremo subampliato ; semi- 
cellulse truncato-pyramidatse, angulis inferioribus et superio- 
ribus subrotundatis, lateribus apicibusque leviter convexis ; 
membrana crassa asperulata dense et irregulariter scrobiculata, 
in centro incrassata ; a vertice visae ellipticae, in medio utro- 
bique tumidae ; a latere visae late ovatae, basem versus tumidae 
utrobique. 
Long. 72 y ; lat. 51 y ; lat. isthm. 17*5 y; crass. 35 y. 
Hah Near Goring, S.E. Oxfordshire. 
This is smaller than the average example of G. p yramiclatum 
Breb., from which it differs in its form, its central elevation, its 
thicker membrane, and in its more marked scrobiculations. 
Only one specimen of this was seen, and the membrane was 
slightly but distinctly rough. 
15. C. tenue Arch. (Cooke, Brit. Desm., p. 92 ; West, Freshw. 
Alg. of W. Ireland, p. 147, pi. xx. f. 25). 
We have seen many specimens of this species with zygospores 
from Scarborough, Maine, U.S.A. Mr. L. N. Johnson has recorded 
it with zygospores from Michigan (Some new and rare Desm. of 
U.S., Bull. Torr. Bot. Club, xxi. No. 7, July 20, 5 1894, p. 288). 
0. melanosporum Arch. (Cooke, Brit. Desm., p. 188 ; Eoy et Biss. 
Scottish Desm., p. 38, pi. iv. fig. 14) seems to differ from this species 
in its relatively longer cells, its broader isthmus, and in its dark 
zygospore. 
16. C. inconspicuum sp. n. PL I Y. fig. 45. 
C. minutum, circiter lj-plo longius quam latius, sinu 
aperto valde excavato ; semicellulae ellipticae, apicibus compressis 
(paene subtruncatis) ; a vertice visae ellipticae ; membrana 
achroa glabraque ; pyrenoidibus singulis. 
Zygospora ovoidea, membrana achroa glabraque. 
Long. 13 *5-14 *5 y; lat. 9*5-11 y ; lat. isthm. 
4 *8-5 *7 y; diam. zygosp. 14*5-17 y. 
Hob. Mitcham Common, Surrey. 
This seems nearest to G. minutissimum Archer, but differs suffi- 
ciently from it, and also from G. melanosporum Arch., G. tenue Arch., 
G. pygmseum Arch., C. tinctum Ealfs, &c., all of which have smooth 
zygospores. 
17. C. ljeve Babh. (FI. Europ. Alg., iii. p. 161 ; Wittr. & 
Nordst. Desm. et (Edog. in Italia et Tyrol., taf. xii. f. 4 : 
