BY G. I. PLAYFAIR. 321 



evenly to the apices, but, when a short distance from the tip, 

 the concave side becomes more or less parallel to the other, 

 making the end subrostrate. Not at all uncommon round Sydney, 

 generally mixed with the type. Quite certainly a form of CI. 

 gracile. 



Closterium pronum Br^b. (PL xli., f.9.) 

 Long. 300, lat. 8-10, ap. 2 /x. Membrana luteola, striis nullis. 

 Kyogle. 



Brebisson, Liste, PI. ii., f.42. Not 67. pronum W. &, G. S. 

 West, Monog., i., PI. 23, f.l-3( = CI. acutum forma major), nor CI. 

 proiium Klebs, Desm. Ostpreuss., p. 19, T. ii., f.l2a( = C7. linea 

 Perty, f. major. The extremities of the cell, it should be noted, 

 s^re filiform, shorter, however, than the part of the semicell in 

 which the chloroplast lies. These details agree exactly with 

 Brebisson's note (Liste, p. 157). Moreover, he unites CI. pronum 

 with CI. setaceum, CI. Kutzingii and others, in a group charac- 

 terised as "Corpuscules fusiformes termines par un long bee sans 

 endochrome (Stauroceras Kiitz.)." CI. pronum is quite unlike 

 the forms of CI. acutum with which Klebs classes it; the mem- 

 brane also is of quite a different character. 



Clostkrium Kutzingii var. capense Nord. 



Lonsf. 285. lat. 15 



II. 



Lismore, Kyogle, cum priori. 



Desm. Lugduno-Batavi, p.l, f.l, including 67. Kutzingii Breb., 

 ibid A small form having, in length, the same range as CI. 

 pronum, in company with which it is nearly always found here. 

 It is more inflated, however, in the centre, the breadth varying 

 generally from 14-16 /a, with about the same relative proportions 

 of body and rostrum as in 67. pronum. Biologically, indeed, it 

 is a form of that species. The ipembrane is usually faintly 

 yellowish and clear, occasionally distinctly striate. 



Cl. PRiELONGUM Breb. (PL xli., f.lO.) 

 Long. 565-770, lat. 14-20, ap. 4-5, subap. 6 /x. 

 Lismore (223, 225, 254, 259, 260). 



This species is characterised by W. & G. S. West, Monog., i., 

 p. 165, as one of the rarest species of the genus. It is not un- 

 9 



