284 W. AND G. S. WEST 



Forma reducta. Cellulee breviores, polls minus productis et distincte truncatis ; 

 striis 13 in 10 /u. 



Both of these forms were common over the whole area in which collections were 

 made. 



34 Navicula muticopsiforme sp. n. (PI. XXVI, Fig. 131) 



N. minutissima, valvis subellipticis, diametro circiter duplo longioribus, parte 

 mediana parva cum marginibus parallelis, polis longe cuneiformibus et obtuse 

 rotundatis, platea centrali magna et transverse dilatata, platea axiali lata, striis 17 

 utrobique (16 in 10 /z), punctatis, in parte mediana (ad versus plateam centralem) 

 striis tribus brevibus e puncto singulo elliptico formatis, ceteris radiatis e punctis 

 duobus formatis. 



Long. 11.3 M; lat. 5.3 M . 

 Hob. Clear Lake. 



This minute species has a slight resemblance to the more reduced forms of 

 N. muticopsis V. Heurck, but differs in the cuneate poles of the valves and in its striae. 

 There is a relatively large central area, caused by the shortening of three striae on 

 each side. These striae are reduced to a single elliptical punctum. The remaining 

 striae, which are somewhat divergent, are disposed in seven pairs in each half of the 

 valve. They leave a rather wide axial area, and each striation consists of two some- 

 what elongated puncta. 



The species should be compared with N. mutica Kiitz. and N. seminulum Grun., 

 from both of which it differs in outward form and in the striation of the valves. 



35 Navicula peraustralis sp. n. (PI. XXVI, Fig. 132) 



N. parva, valvis anguste lineari-lanceolatis, diametro circiter 4j-plo longioribus, 

 lateribus triundulatis inflatione mediana majori, polis inflato- capita tis et levissima 

 angularibus, platea centrali parva et elliptica, platea axiali angusta, striis validis 

 18 in 10 /u, leviter radiatis, a plateis lateralibus duobus interruptis. 



Long. 47.7 /u; lat. 11.1 p.. 



Hob. Recent geological deposit containing subfossil diatoms. 



This species is similar to those of the N. mesolepta group, but does not agree with 

 any of them. The two lateral areas interrupting the striations are also very 

 characteristic. In general outline it is not unlike N. semicruciata Ehrenb., as 

 figured in A. Schmidt's Atlas Diat. t. 44, f. 45. 



36 Navicula (Pinnularia) globiceps Greg. 



Cleve, Synops. Name. Diat. II, 1895, p. 77. 



Long. 23-25 M; lat. 9-9.5 /m; striis 18 in 10 M . (PI. XXVI, Fig. 135) 



Hob. Green Lake and Clear Lake. Recent geological deposit containing diatoms. 



In one half of the central area was a single isolated punctum. The striations in 

 the median part of the valve were interrupted by two longitudinal lines, and in the 

 region of the capitate poles by one longitudinal line. 



