12 P. T. CLEVE, ON SOME NEW DIATOMs. 
19. Navicula amica Cx. et Grun. 
Contracted in the middle, ends cuneate; strix 7'/, in 0,01 mm., almost parallel, 
smooth. The two interior rows of strie are interrupted in the middle. 
Length 0,075 mm. Breadth 0,023 mm. 
Pls Uy tie Bie 
Tahiti (Eugenie Exp.). 
20. Navicula quadriseriata Cu. et Grun. 
Large, oblong oval with parallel sides and cuneate ends. Striz smooth, 8 in 0,01 
mm. in four longitudinal, uninterrupted rows. The interior strie are shortened around 
the central nodule, which is surrounded by an orbicular area. 
Length 0,09 mm. Breadth 0,035 mm. 
Pl. HE, fig; 33, °°). 
Balearic Islets very rare (F. SépERLUND). 
Two other species, of which Mr. Grunow has sent me figures, seem to be related 
to the last described forms: NV. Castracanei Grun. (PI. III, fig. 33, °°°/,) and N. Petitiana 
Grown. (Pl. III, fig. 34, °°°/,). Both species are elliptic lanceolate and have the interior 
rows of striz parallel with the margins of the valve, not close to the median line. 
N. Castracanei is 0,1 mm. in length, 0,03 mm. in breadth, and has 9 strie in 0,01 mm. 
N. Petitiana is 0,07 mm. in length and 0,02 mm. in breadth and has 11 striz in 
0,01 mm. 
All these species together with the following seem to form a section, for which 
Mr. Grunow has proposed (Cx. et Grun. Art. Diat. pag. 29), the name quadri-seriate: 
This group contains: 
Navicula Powelliti Lewis = N. Vidowichii Gruy. 
Egyptiaca GREv. 
(Powelltt var.) Gallapagensis Cu. 
Zanardiniana GRUN. 
Wittii Grown. 
amica CL. et Grun. 
quadriseriata CL. et Grun. 
Castracanet GRUN. 
Petitiana Grun. 
? N. (Stauroneis) robusta Petir (Diat. de Vile Campbell Pl. V, fig. 16). 
N. biseriata Petit (1. c. Pl. IV, fig. 15). 
N. Richardsoniana O'Meara (Irish Diat. Pl. 31, fig. 33). 
N. Eugenie Cu. (this paper pag. 7). 
? N. denticulata O'Mzara (Quart. J. M. S. VI, p. 115, Pl. V, fig. 2, 1867). 
? N. Musca Exp. 
? N. mirabilis Leupucer Forrmorer (Diat. de Ceylon Pl. II, fig. 21). 
N. blanda A. Scum. (Nordsee Diat. Pl. II, fig. 27). 
N. latefasciata Grun. (in Cu. et Grun. Arct. Diat. Pl. I, fig. 21), 
