12 
Transactions of the Society . 
Var. minor isthmo angustiore et angulis rotundioribus. 
Long. 62 fi; lat. 60 /x ; lat. isthm. 13 *5 /x. 
Hah. Glen Shee, Perthshire, Scotland. 
S. subavicula sp. n. [ = St. arcuatum Nordst., snb3p. subavicula 
West, Freshw. Alg. of Eng. Lake District, p. 732, pi. ix. f. 25]. 
Dr. 0. Nordstedt (in litt.) has pointed out that this cannot be a 
variety of his S. arcuatum , consequently it must rank as a distinct 
species. 
S. Ophiura Lund. (Desm. Suec., p. 69, tab. iv. fig. 7). 
var. Cambricuh var. n. 
Var. cellulis lj-plo latioribus quam longioribus (cum 
processibus) ; semicellulae cuneatae, lateribus leviter 
concavis, apicibus cum annulo verrucarum conicarum 
(non emarginatarum) 8 ornatae, radiis brevioribus, 
denticulatioribus in margine superiore convexo; a 
vertice visae 8 (raro 6, 7 et 9) radiatae. 
Long. 75-80 /x; lat. cum proc. 98-110 (usque ad 
145) y , ; lat. isthm. 16-18*5 fx. 
Hah. Capel Curig, N. Wales. 
This is the same as S. Ophiura Lund, figured by Cooke and 
Wills, Grevillea, 1880), also in Cooke’s Brit. Desm., pi. 59, f. 1, not 
the description on p. 172 (which is a translation of that of Lundell, 
where the apical papillae are described in front view as bifid, and in 
vertical view as quadrifid ; Cooke’s figure shows that the papillae of 
the British examples were entire, and not like the Swedish). The 
8-rayed forms are the most common. At the base of each semicell 
there is a ring of 12 rather long papillae (not figured by Cooke). 
S. irregulare sp. n. Figs. 49, 50. 
S. parvum, paullo longius quam latius, modice constrictum, 
incisura mediana minuta ; cellulae semper tortae ; semicellulae 
trapezicae, apicibus glabris et subconcavis ; angulis superioribus 
in processibus brevibus crenulato-denticulatis divergentibus 
productis, apice processus bidenticulato ; a vertice visae bira- 
diatae subirregulares, medio utrobique projectione prominenti 
truncata subdenticulata ad apicem ; a latere visae subirre- 
gulares, projectione ad basim utrobique. 
Long, cum proc. 15*3-18*2 jx; sine proc. 9 *4-9 *6 fx ; 
lat. cum proc. 13*5-17*3 fx; lat. isthm. 4 *8-5 *7 /x ; crass. 
6 * 6-7 ' 7 ju. 
Hah. Ballynahinch, Co. Galway, Ireland. 
This seems a very characteristic species, probably coming nearest 
to St. tetracerum Balfs. 
