KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 22. NIO 8. 53 



16. C. pseudopachydermiim nov. spec. Tab. 5, fig. 20. 



Cosmarium Ralfsii Mask. N. Z. D. p. 316, tab. 12, fig. 30?? 



C. maximum diametro 1 7 3 -plo longius, medio profunde constrictum iiicisura sub- 

 lineari angusta (extremo ampliata); semicellula? (circulari-pyramidales) e basi recta fere ad 

 medium aaquali latitudine lateribus subrectis, ab hoc loco vel sa?pe ad angulos inferiores 

 sensim angustatas lateribus couvexis apice rotundata? vel vulgo medio apice truncatse vel 

 nonnumquam subretusae, angulis inferioribus subrectis obtusis; a vertice visas late elliptica?., 

 a latere latissime elliptica?. Membrana crassa distincte dense punctata. Latitudo apieis 

 (truncati) circ. tertia pars latitudinis semicellulse. Nuclei amylacei bini laminis chloro- 

 phyllaceis senis (ut in Cosm. Candiano Delp. Desm. ital. p. 113, tab. 8, fig. 1—3). 



Magnitudine ab omnibus speciebus confinibus differt, praeterea a C. pachydermo 

 Lund. longitudine majore et semicellulis apicem versus magis attenuatis; a C. py ramidato 

 Bréb. lateribus magis convexis, membrana crassiore dissimiliter punctata, a C. Cucumi 

 dispositione massa? chlorophyllaceae etc. 



Long. 144 — 168 ,"; lat. 98 — 110 ,«; lat. isthm. 46 — 56 ,«; crass. 71 — 75 ,«; crass. 

 membr. ad 3 //. 



Waimakariri river (5); Artbur Pass (17); Lake Lyndon (20); Teremakau et Arabura 

 (22); Orakeikorako (293). 



As far as I have been able to juclge from specimens preserved in Liquor Hantzschii 

 the structure of the cell contents is such as in Delponte's figure 1. c In general the two 

 amylaceous vesicles were distinctly seen, but not tbe chloropbyll lamina:. The first impres- 

 sion I received of this plant was that it came very near to C. pachydermum Lund., but 

 I consider that it is distinct from it, by the size being larger, by the semi cells tapering 

 more towards the top, and by their length' being proportionately greater. It was more 

 rarely that the apex (of half grown specimens?) were perfectly rounded. In most cases 

 it. is more or less truncated and then frequently depressed in the middle. I have however 

 not met with any membrane so much incrassated in the apex as in Maskell's figure 1. c, 

 for I suspect that his figure may be referable to my species, the more as its size in no 

 way forbids this supposition. But M.'s figure is somewhat broader. (Long. 183 /u, lat. 

 128 — 134 ju; Ig: It — 1 : 1,43 — 1,36. In C. pachydermo Ig : It = 1 : 1,23 — 1,35; in C. pseudo- 

 pachydermo — 1 : 1,51 — 1.5*). 



Regarding the shape of its cells this species is very approximative to Cosm. pyra- 

 midatum, but the lower parts of the sides of the semicells commonly are more parabel, 

 the membrane is thicker and the puncta different. In C. ps.-pachyd. the thick membrane 

 is full of fine canals close to each other and appearing to pass through the whole mem- 

 brane, with the exception perhaps of just the exteriör part. In C pyramidatum the puncta 

 consist of larger but more rare excavations in the thinner membrane. In C. pyramidatum 

 there is a short depression in the centre of the semicells (f. excavata mihi Sycll. Norg. 

 Desm. p. 18), but in C. pseudopachydermum there is nothing of the kind. 



