FRESHWATER ALG/E 285 



37 Navicula (Pinnularia) murrayi sp. n. (PI. XXVI, Fig. 129) 



N. parva, valvis linear!- ellipticis, diametro circiter 4-plo longioribus, polis obtusis 

 laevissime dilatatis, platea centrali transverse expansa, marginem utrinque psene 

 attingente, cum puncta solitaria asymmetrica, platea axiali angusta, striis 14 in 10 M, 

 punctulatis, in to to radiatis, in parte mediana 4 (circ.) utrobique multe brevioribus. 



Long. 45 /a.; lat. 11.5 n- 



Hob. In pond, and moraines near the camp,~Cape Royds. 



This species stands nearest to N. reinhardtii Grun. (cf. V. Heurck, Synops. Dial. 

 Belg. p. 86, t. 7, f. 5, 6 ; = N. vernalis Donkin), but differs in the form of the central 

 area, with its solitary unilateral puncta, in the shorter striae bordering the central 

 area, and in the much closer stria tions (which are 14 in 10 M as compared with 9 in 

 10 fi). The striations are also radiate throughout, and never transverse at the poles, 

 which are very slightly dilated. 



Var. elegans var. n. (PI. XXVI, Fig. 130) 



Var. minor, polis valvae angustioribus, productis et subcapitatis ; striis 15 in 10 yu. 



Long. 31 n; lat. 8.1 /x. 



Hob. Pond, Cape Royds. 



This variety should be compared with N. salinarum Grun. (in Cleve et Grun. 

 " Beitr. Arctisch. Diat.," Kongl. Sv. Vet.-Akad. Handl. Bd. 17, No. 2, 1880, p. 33, 

 t. 2, f. 34), from which it differs in many respects, although the spacing of the striae 

 is the same. 



38 Navicula (Pinnularia} cymatopleura sp. n. (PI. XXVI, Figs. 133, 134) 



N. minutissima, valvis sublinearis, diametro 4J- 5-plo longioribus, lateribus 

 triundulatis, undulo mediana levissime majori, polis subcapitatis, platea centrali 

 magna et longitudinaliter elliptica, platea axiali lata, striis brevibus et laevibus, 

 20-21 in 10 m, leviter radiatis, in parte mediana (adversus plateam centralem) 

 brevioribus. 



Long. 17-27 /; lat. 4-5 a. 



Hub. Clear Lake. Lake on west side of McMurdo Sound. 



This minute species occurred abundantly in the above-mentioned lakes. It is 

 one of the N. mesolepta group, but the poles are much too wide for any form of 

 2V. mesolepta, and the striations are too fine. The iindulate sides are not quite parallel, 

 as there is a gradual and almost imperceptible attenuation. N. rupeslris Hantzsch is 

 of a similar shape, and there is a similar reduction of the striations in the middle of 

 the valve (vide A. Schmidt's Atlas Diat. t. 45, f. 45-48), but the striations oi N. cymato- 

 pleura are finer and shorter than in any of these forms. 



It should be carefully compared with Pinnularia gracillima Greg., P. appendiculata 

 Ag., and P. undulata Greg. The latter is figured in Cleve's " Diatoms of Finland," 

 Acta Soc. pro fauna et flora Fennica, VIII, No. 2, 1891, t. 2, f. 8, and is at once seen to 

 be quite a different diatom. 



