Algae. 589 



collecting (day, month and hour); 7. the Protophytes and Protozoa con- 

 tained in the sample. The rare organisms are not recorded in the tables, 

 but in a separate list. 



A brief review of the general character oi the plankton follows: 



Voyage out: The North Sea contains Triposplankton (p. 147). 

 Around Fair Is!e oceanic forms (Peridinium ovatum, P. pallidum, Rhizo- 

 solenia semispina) occur mixed with neritic ones. — The Plankton of 

 the North Atlantic (from Long. 4° W.) contains every-where Coccolilho- 

 phora pelagica, but is otherwise variable; at Long. 15°— 31° it is charac- 

 terized by containing Thalassiothrix Frauenfeldii ; at Long. 31 u — 36" by 

 Chaetoceras periivianum, etc ; while the Polar Curent oi the east coast 

 of Greenland is filled with Trichoplankton (Thalassiothrix longissima; 

 Coscinodiscus marginatus ; Rhynchomonas marina) and strangely enough 

 Rhizosolenia styliformis, which is otherwise a warm water form. Homeward 

 route: Around Cape Farewell occurred a curious, partly Icelandic- 

 neritic, partly eastern-oceanic Plankton which may be explained by the 

 fact that water from the east part of the North Atlantic Ocean, 

 containing oceanic forms, has during the summer months flowed on to- 

 wards the north-west tili it has touched the south coast of Iceland, 

 whence it has taken along with it some neritic forms and has then gone 

 on along the coast westward to Irminger Sea where a part of the 

 water in question has been carried along by and mixed up with the 

 Polar Current from off the east coast of Gre enl and, from whence also 

 some forms occur. A similar circulation of water is mentioned and figu- 

 red by Ryder. — The warm part of the route in the Atlantic Ocean 

 contains variations of Scoticaplankton. 



As Dr. Steenstrup's apparatus works continually and gives pure 

 samples, these gatherings are useful to control and to compare with the 

 usual collections made on the routes to Iceland and Greenland 

 which have hitherto been investigated by Ostenfeld. A comparison 

 shows 1. that it is sufficient to collect about 15 samples on a voyage 

 across the North Atlantic at Long. 58" — 60° W. ; this will furnish one with 

 Plankton from the existing ocean-currents ; 2. that as a rule there are 

 no sharp boundaries between these; still the dividing line between the 

 North Sea and the North Atlantic is clearly defined; 3. that the 

 specimens which inevitably remain attached to the meshes do not affect 

 the results if care be taken that several samples are collected with the 

 same net; 4. that Steenstrup's method gives a somewhat different result 

 in regard to the relation between the quantities of the organisms col- 

 lected, than is obtained by the usual method, as the surface of the small 

 filtering gauze is very soon filled up, and is at last completely blocked, 

 so that many small forms are caught which otherwise would escape, e. g. 

 Coccolithophora, Syracosphaera. etc.. 5. A comparison betwen these col- 

 lections and those gathered at about the same time on the same route, and 

 published previously by Ostenfeld shows that a fairly good conformity 

 exists between the Plankton-associations. Further it is clear that the 

 point at which every Single organism occurs lies further westward, at 

 the end than at the beginning of the season 



Finally these investigations show that there cannot be proved to 

 exist a strict connection between the colour of the sea water and the 

 nature and relative quantity of the Plankton, still, on the whole, there is 

 a general connection, the usual rule being that a yellowish green water 

 is richer in Plankton than is the blue water. C. H. Ostenfeld. 



TONI, G. B. DE, e d ACHILLE FORTI, I n t o r n o a 1 Byssus purpurea 



del Lightfoot. Nuove osservazioni. (Atti del Reale 



Istituto Veneto di scienze, lettere ed arti Tomo LXIH, parte 



seconda. 1904. p. 205—210.) 



Während einer Reise in Grossbritannien haben Verff. die 

 wenig bekannte Rothalge Byssus purpurea Lightf. an dem klassischen 



