26 P. T. CLEVE, ON SOME NEW DIATOMS. 
short rows, 5 in 0,01 mm. In the angles the puncta are much smaller and form fine 
branching lines. 
Distance between angles 0,0975 mm. 
Pl, V1, Be Te ee 
Gallapagos Islands rare (Eugenie Exp.). 
9. Triceratium margaritiferum Cu. N. Sp. 
Valve quadrangular with concave sides and rounded angles, without processes. 
Surface probably plane. Structure tolerably coarse granules arranged near the margins 
in short lines, smaller in the angles, rare and scattered in the middle. 
Diam. 0,05 mm. 
PL VE) he. Fh 
Gallapagos Islands rare (Eugenie Exp.). 
Chetoceros Exs. 
1. Chetoceros Dicheta Ens. = C. remotus Ci. et GRUN. 
This form has already been described in Cx. et Gruy. Arct. Diat. p. 119 and is 
to be found in most slides of Cru. et Mézy. Diat. N:o 125. 
PLM, tee Th ie 
Antarctic Ocean (Challenger Exp.). 
Rhizosolenia Euxs. 
1. Rhizosolenia (alata var.?) gracillima Cv. 
Extremely long and slender, measuring 0,5—0,7 mm. in length and only 0,006 
mm. in breadth. The beaks are almost straight, provided with pocket-like impressions. 
The zig-zag markings on the connecting membrane are very indistinct. The frustule 
is extremely hyaline, having no colour in dry state. No structure has been seen. 
Pi Vi, fis. 75, PP"), 
West coast of Sweeden, Lysekil, freely floting on the surface of the sea (July 
1877 by P. T. Creve). 
Another slender species, characterized by its coarse, of puncta composed striz, 
Rh. Shrubsolai Cr. N. Sp., occurs in the Atlantic Ocean between Iceland and Green- 
land. It was recently found in great abundance on the surface of the sea near the 
island of Sheppey by Mr. Sarussoxe. 
