12 P. T. CLEVE, ON SOME NEW Dl ATOMS. 



19. Navicula amica Cl. et Grun. 



Contracted in the niiddle, ends cuneate; stria; 7V2 i" 0,01 mm., almost parallel, 

 smooth. The two interiör rows of strias are interrupted in the middle. 

 Length 0,075 mm. Breadth 0,023 mm. 



Pl. III, tig. 37, ^'7i. 

 Tahiti (Eugenie Exp.). 



20. Navicula quadriseriata Cl. et Geun. 



Large, oblong oval with parallel sides and cuneate ends. Striaj smooth, 8 in U,ol 

 mm. in four longitudinal, uninterrupted rows. The interiör stria3 are shortened around 

 the central nodule, which is surrounded by an orbicular area. 



Length 0,09 mm. Breadth 0,035 mm. 

 Pl. III, fig. 32, -Vi- 



Balearic Islets very rare (F. Söderlund). 



Two other species, of which Mr. Grunow has sent me figures, seera to be related 

 to the last described forms: N. Castracanei (ymj^. (Pl. III, fig. 33, ""Vi) and N. Petitiana 

 Grun. (Pl. III, fig. 34, °"7i)- Both species are elliptic lanceolate and have the interiör 

 rows of strife 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 striaä iu 0,01 mm. 

 N. Petitiana is 0,07 mm. in length and 0,02 mm. in breadth and has 11 striaj in 

 0,01 mm. 



All these species together with the following seem to form a section, for which 

 Mr. Grunow has proposed (Cl. et Geun. Art. Diat. pag. 29), the name quadri-seriatoe : 

 This group contains: 



Navicula Powellii Lewis = N. Vidowichii Grun. 



N. Egyj^tiaca Grev. 



N. {Powellii var.) Gallapagensis Cl. 



N. Zanardiniana Grun. 



N. Wittii Grun. 



N. amica Cl. et Grun. 



N. quadriseriata Cl. et Grun. 



N. Castracanei Grun. 



N Petitiana Grun. 



? N. {Stauroneis) robusta Petit (Diat. de Tile Campbell Pl. V, fig. 16). 



N. hiseriata Petit (1. c. Pl. IV, fig. 15). 



N. Richardsoniana 0'Meara (Irish Diat. Pl. 31, fig. 33). 



N. Eugenice Cl. (this paper pag. 7). 



? N. denticidata 0'Meara (Quart. J. M. S. VII, p. 115, Pl. V, fig. 2, 1867). 



? N. Musca Ehb. 



? N. mirabilis Leuduger Fortmorel (Diat. de Ceylon Pl. II, fig. 21). 



N. blanda A. Sci-iM. (Nordsee Diat. Pl. II, fig. 27). 



N. latefasciata Grun. (in Cl. et Grun. Aret. Diat. Pl. I, fig. 21\ 



