10 
Transactions of the Society. 
Genus Staurastrum Meyen ; Ealfs. 
S. dejectum Breb. (Ealfs, Brit. Desm., p. 121, tab. 20, fig. 5). 
* Tellamii subsp. n. Fig. 45. 
S. mediocre, paullo latius quam longius (sine acul.), pro- 
funde constrictum, sinu acutangulo ; semicellulse obverse sub- 
semicirculares, dorso subtruncatse et retusae, angulis subobtusis, 
aculeo longo horizon tali instructs ; a vertice visae triangu- 
lares, lateribus concavis, angulis subattenuatis, aculeo longo 
instructis. 
Long. 19 fjb ; lat. sine spin. 21 /x ; lat. cum spin. 48 /x ; 
lat. isth. 6*5 /x. 
Hob. Gun wen Moor, Cornwall. 
This differs from S. dejectum Breb. in its longer, stouter, almost 
parallel spines and from S. megacanthum Lund, in its retuse apex, its 
less valid spines, its less attenuated angles, and in its much smaller 
size. 
S. lunatum Ealfs. Brit. Desm., p. 124, tab. 34, fig. 12. 
var. subarmatum var. n. Fig. 47. 
Yar. angulis attenuatis in spinam mucronatam. 
Long. 30 fi; lat. c. mucr. 33 /x; lat. isthm. 11*5 /x. 
Hab. Derryclare Lough, Connemara, Ireland. 
S. avicula Breb. var. subarcuatum (Wolle) nob. [= St. sub - 
arcuatum , Wolle Desm. U.S., p. 140, pi. xlvi. figs. 15-16 ; 
St. avicula Breb, var. verrucosum West, Fresh w. Alg. of 
W. Ireland, p. 174, pi. xxiii. fig. 2 ; St. denticulatum (Nag.) 
Arch, as figured by Elfving, Anteck. Finska Desmid.]. 
Punctate and finely granulate examples of St. avicula occur more 
frequently than the glabrous forms. It is to the roughly granulate 
form that this variety applies. Wolle (1. c.) remarked that his species 
would be equally well placed as a variety of St. avicula ; and as the 
Irish and American plants are identical, they are united as a variety 
of this species. 
S. furcatum (Ehrnb.) Breb. 
var. subsen arium var. n. Fig. 53. 
Yar. cum spina simplici infra utramque spinam dor- 
salem bifurcatam. 
Long, sine spin. 29 /x ; lat. cum spin. 39 /x ; lat. sine 
spin. 32*5 /x; lat. isthm. 9*5 /x. 
Hab. Leenane to Westport, Co. Mayo, Ireland. 
The vertical view of this variety somewhat resembles that of 
S. senarium (Ehrnb.) Ealfs, but the lower spines of the former are 
simple. 
S. amphidoxon sp. n. Fig. 17. 
S. parvum, subduplo latius quam longius, profunde con- 
strictum ; semicellulse subellipticae granulatae, granulis in 
