C. H. Ostenfeld: A List of Phytoplankton from the Boeton Strait, Celebes. 13 



Coscinodiscus Castracanei nom. now; C. centralis var. nov., 

 «Castracane, Challenger Rep, 1886, p. 155, pi. 2, fig. 3; ? C. oculus 

 iridis Ostenfeld, Botan. Tidsskr., 25, 1902, p. 222; non C. centralis 

 Ehbg., nec C. oculus iridis Ehbg. 



Diam. ca. ?00 fi; valvæ planæ; rosula centralis obvia; areoli sat 

 magni, radiati; apicnli marginales 

 desunt; copula annulata dense striata. 

 Chromatophora haud numerosa, parva. 



This species is easily known 

 when seen from the girdle, which is 

 densely and finely striate. The valve 

 has about the same structure as 

 that of C. oculus iridis, but is quite 

 flat (fig. 6). 



As my specimens agree well 

 with the form figured by Castracane 

 as i>C. centralis var. nov.«, I have 

 named it C. Castracanei. It differs F i g . 6 Coscinodiscus Castracanei 

 from the true C. centralis by the nom. nov. a, valvar view; b, girdle 

 absence of any apiculi at the mar- view. (^p). 



gin and by the flat valves, and does 



not at all belong to the same group, that which I have called 

 Biapiculati. 



C. Janischii A. Schmidt, Atl. d. Diatomaceenkunde, PI. 64, figs. 

 3—4; C. arafurensis var. nov., Castracane, 1. c, p. 153, pi. 2, fig. 4; 

 C. craspedodiscus Castracane, ibid., pi. 3, fig. 5. 



Fragments of this large species were not rare in the sample. 



C. Jonesianus (Grev.) nob.; Eupodiscus Jonesianus Greville, Trans. 

 Microsc, Soc, 1862, p. 22, pi. 2, fig. 3; E. ? commutatus Grunow, 

 Denkschr. Wien. Akad. math. Nat. Kl., 1884, p. 79, ex minima parte; 

 Cose, radiatus, var. Jonesianus Van Heurck, Treatise Diatom., 1896, 

 p. 531, ex minima parte; ? Coscinodiscus sp. A. Schmidt, 1. c, 

 pi. 60, fig. 16. 



Diam. 200 — 280 u.; valvæ plano-convexæ ; rosula centralis ex 

 areolis majusculis cfformata; areoli ceteri sat delicati fere ut in 

 C. Granu Cough; series rectæ, + fasciculatæ ; apiculi numerosi sub- 

 marginales uniseriati delicati, duo autem magni, conici, cavi, fere ut 

 in C. commutato Grun.; apiculi non pauci, delicatissimi in orbem 

 irregulärem fere dimidium inter centrum et marginem ducli ; copula 

 rcgnlari (non obliqua), ca. 50 — 60 (Li lata. Chromatophora numerosa, 

 sat magna. 



In a paper on the phytoplankton of the Aral Sea (Wiss. Ergebn. 

 Aralsee-Exp., Lief. VIII, Isw. d. Turkest. Abt. d. k. Russ. Geogr. Gesellsch. 

 IV, St. Petersburg 1908) I have created the group Biapiculati for those 

 Coscinodiscus species which have: a radiate arrangement of the 

 areoles with some larger ones in the centre, a single row of small 

 apiculi near the margin of the valve and two larger apiculi in this 

 row, the angle between those two being larger than 90°, smaller 

 than 180°. To this group were referred: C. Granu Gough, C. ara- 



