10 



Rhiz. |). IJl, PI. 3, f. G) , from which it differs mainly in the form of 

 the spine. 



1(1 (r). 



25. R. calcar avis SchuUze in Miill. Arch. 1858, p. 339, PL 13, f. 5-10; 

 Peragallo, Monogr. Rliiz. p. 113, PI. 4, f. 9, 10; Cleve, DiaL f. the Sea of 

 Java, p. 1 1 ; Atl. Plankt. Organisrnus, p. 339 ; PL f. the Ind. Ocean and 

 the Malay Archip. p. 22; Schroder, Neapel, p. 26. 



The type has been fonnd in a few specimens, which are quite like 

 the specimens from the North Sea, but commonly it is remplaced by the 

 variety, var. cochlea, mentioned below. 



I (rr) — 10 (rr). 



Area: Along the Atlantic coasts of Europe, Africa and America; Mediter- 

 ranean, Malay Archipelago. 



R. calcar avis Schultze, var. cochlea (Brun) 



Ostf. ms.; R. cochlea Brun, Diat. foss. et pelag. 



1891, p. 43, PL 19, f. 9; Peragallo, Monogr. Rhiz. 



p. 113, PL 4, f. 11; Cleve, PL f. the Ind. Ocean 



and the Malay Archip. p. 22 and p. 56, PL 8, f. 12; 



Leuduger-Fortmorel, 1. c. p. 36; de Wildeman, 



I.e. p. 123. 



Cleve has figured a fragment of a frustule 

 showing numerous, small chromatophores grouped 

 in oblique or spirally twisted bands, but the 

 rather numerous specimens which I have seen, 

 had the small chromatophores in more or less 

 distinct longitudinal bands. I consider it a variety 

 of R. calcar avis, corresponding to the var. indica 

 of 7?. a! at a. 



Fig. 5. Bhisosolenia calcar '■) (vv) 3 frr1 — (Hrr) lOf-1-) 



mns Scliultze var. cochlea -^i ) y > y > ^"^^ 



(Brun) Ostf. (15^). Area: Indian Ocean, Malay Archipelago. 



Fig. 6. Rhizosolema Clevei Ostf. {~^)- 



