8 DH. GREGORY, ON SOME NEW SPECIES 



in form close to iV. lepida, but the nodule retained its charac- 

 teristic aspect 



26. Navicula incurva, W. G. — This eleg'ant species I have 

 observed in two or three gathering's from the River Findhorn, 

 and very sparingly in that from Lochleven. It is rather 

 narrow, witli somewl.at angular shoulders, contracted suddenly 

 toward:j the apices, which are produced and square, and 

 more gently towards the centre. Length about '00] 7 inch. 

 Tiie striae have not yet been resolved. It seems to belong to a 

 group, all of which have irresolvable striae, such as JV. producta 

 and JV. crffims ; but its very characteristic and constant form 

 render it quite distinct. 



27. Navicula longiccps, W. G. — This little form occurs in 

 the Morayshire and Banffshire gatherings along with the equally 

 minute species Pinnularia linearis, P. suhcapitata, P. gracil- 

 lima, and N. bacillnris. It is small, linear, narrow, but not 

 very long, contracted near tlie extremities, and subsequently 

 continuing of uniform width to the broadly rounded apices. 

 Nodule indefinite, striae not yet resolved. Length about -0012 

 inch. It is more frequent in the Elctiies gathering than in 

 any of the others, and is very permanent in its characters. I 

 have named it, from the peculiarly long shape of the con- 

 tracted ends. 



28. Pinnularia biceps, W. G. — This well-marked form 

 occurs in the gatherings from Elgin, Elchies, and Lochleven, 

 as well as in some others, and is by no means rare. It is 

 rather large, linear, contracted towards the ends, and expand- 

 ing into large round heads. The striae which liave, as in P. 

 divergens, three centres of radiation, do not reach the median 

 line, and towards the central nodule leave a large round blank 

 space, on the sides of which of course the striae are much 

 shortened. There are two varieties : iS, which is less con- 

 stricted and subrapitate ; and y, which has tliree undulations 

 on each side, and is capitate like the type. Length from "002 

 t') 'OOS incli. Striae about 24 in "001 inch. This species ap- 

 proaches to P. divergens, which, however, is not capitate, and 

 besides has the central blank space in the form of a broad 

 false stauros, reaching to the margin, so that there are no striae 

 on either side of the central nodule. 



29. Pinnularia linearis, VV. G. — This little form occurs in 

 the gatherings from Elgin, Elchies, and several other Banff- 

 shire localities, also in Lochleven and elsewhere. It is small, 

 linear, narrow, very slightly narrower at the apices, and occa- 

 sionally a little contracted just before them. The striae are 

 fine, very nearly parallel, reaching the median line. Nodule 

 small, somewhat elongated ; it has a distinct border, formed 



