12 



Dansk Botanisk Arkiv, Bd. 2, Nr. 4. 



Several of Dr. Justesen's drawings seem to represent this species 

 which is perhaps only the tropical race of the northern Ch. decipiens Cleve. 

 Ch. paradoxum Cleve, 1. c, 1873, p. 10, pi. 3, fig. 16. 

 Drawn by Dr. Justesen. 



Ch. peruvianum Brightwell, Microsc. Journ., 1856, p. 107, pi. 7, 

 fig. 16; Gran, 1. c, 1905, p. 70. 



Drawn by Dr. Justesen and not rare in the sample. 

 Ch. polygonum Schutt, Ber. Deutsch. Bot. Ges.. 1895, p. 46; 

 Ch. pol, forma Schroeder, Vierteljahrsschr. Naturf. Ges. Zürich, Jahrg. 

 51, 1906, p. 348, fig. 8. 



A form agreeing well with Schroeder's figure was drawn by 

 Dr. Justesen. 



Ch. Schmidtii Ostenfeld, Vid. Medd. Naturh. Forening, Køben- 

 havn, 1901, p. 155, fig. 8. 



Several drawings are very like the species which I have 

 described from the Bed Sea and the Gulf of Siam. 



Ch. secundum Cleve, 1. c, 1873, p. 10, pi. 2, fig. 14; Ch. curvi- 

 setum Cleve, in Kanonbaaden Hauchs Togter, Kjøbenhavn 1889, p. 55 

 with fig.; Gran, 1. c, 1905, p. 91. 

 Drawn by Dr. Justesen. 



Ch. tetrastichon Cleve, A Treatise of Phytoplankton, 1897, 

 p. 22, pi. 1, fig. 7. 

 As the foregoing. 



Ch. Vanheurckii Gran, Norske Nordhavs Exp., Protophyta, 1897, 

 p. 18; Ostenfeld, Botan. Tidsskr., 25, 1902, p. 240, figs. 18-19. 

 As the foregoing. 



Corethron criophilum Castracane, Challenger Bep., 1886, p. 85, 

 pi. 21, figs. 12, 14, 15; C. hystrix Hensen, V. Ber. Kommiss. in Kiel, 



1887, p. 89, pi. 5, fig. 49; C. 

 pelagicum Brun, Mém. soc. de 

 phys. et d'hist. nat. Geneve, vol. 

 31, pt. II, no. 1, tab. 19, fig. 6; 

 B. Schroeder, 1. c, p. 343, fig. 3. 

 Two drawings by Dr. Justesen 

 have been referred to this widely 

 distributed species. — 



None of the drawings of Cosci- 

 nodiscus-forms showed any struct- 

 ure of the valves, they were 

 therefore quite useless. But this 

 drawback was much diminished, 

 as the sample contained several 

 Coscinodisci which could be re- 

 ferred to species, only the larger 



c-i« c /^„„-„ j- -*u n ones being broken to pieces, 



rig. 5. Coscinodiscus sp. with many small ö , . r 



Cocconeis sp. attached to the girdle. Amongst the drawings were 

 (Drawn by Dr. Justesen). two showing how the Coscinodisci 



are used as hosts for smaller 

 diatoms. I reproduce one of them (fig. 5): The Coscinodiscus wears 

 11 individuals of Cocconeis sp. around the girdle. 



