MICEASTERIAS. 93 



Var. glabra Norclst, (PI. XLIV, figs. 4, 5.) 



M. papillifera Breb. var. glabra Norclst. in Wittr. & Noi'dst. Alg. Exsic. 

 1882, No. 466; in fasc. 21 (1889), p. 35; West Alg. W. Ireland, 1892, 

 p. 135. 



Cells destitute of the acute granules or denticula- 

 tions which are normally present on both sides of the 

 principal incisions. 



Length 90-125 p; breadth 88-109 p.; breadth of 

 isthmus 19 /x. 



SCOTLAND.- -Near Tarbert, Harris, Outer Hebrides ! 



IRELAND. Ballynahinch, G-alway ! 



Geogr. Distribution. X. Russia. Brazil. 



A form of this variety was described from the west of 

 Ireland as "var. glabra Nordst. forma inflata "West," in which 

 there was a small basal inflation in the side view of the semi- 

 cells. This form is figured on PI. XLIV, fig. 5 (length 125 /LI 

 breadth 125 /u; breadth of isthmus 15 fi ; thickness 29 p). 

 Consult West, ' Alg. W. Ireland/ 1892, p. 135, t, 20, f. 10. 

 Nordstedt has suggested that this form is possibly a small speci- 

 men of M. denticulata var. not at a, but we do not think so. 



Var. varvicensis Turner. (PL XLIY, fig. 6.) 



M. papillifera Breb. var. varvicensis Turner, Desm. Notes, 1893, p. 345, 

 fig. 13. 



" A variety with the lobes and lobules incised 

 almost as in M. Crux-Melitensis." The interlobular 

 incisions are considerably more open than in the 

 typical form. 



Length 128 /*; breadth 120 /x; breadth of isthmus 

 26 p,. 



ENGLAND. Button Park, Warwick (T. Bolton). 



8. Micrasterias Murrayi "West & Gr. S. West. 



(PL XLV, %s. 1-3.) 



Micrasterias Murrayi West & G. S. West, Scott. Freslrw. Plankton, I, 

 1903, p. 538, t. 15, figs. 1, 2. 



Cells of medium size, as broad as long, very deeply 

 constricted, sinus widely open with an acute apex; 

 semicells broadly subsemicircular and deeply 5-lobed, 



