28 LÖNNBERG, THE BIOLOGY OF THE CASPIAN SEA. 



Professor Cleve kindly communicates about this sample: 



yCoscinodiscus commutatus Grun. (D. Diat. von Franz Josefs- 

 Land, pag. 79). Grunow mentions this form from Cuxhafen, 

 Brazil, China, Java and Peru guano. — This species is the most 

 common in the collection and seems not to be anything but a 

 variety of C. concinnus W. Sm.» 



•»Actinocyclus Ralfsii W. Sm. not rare in the gathering from 

 Baku. The same form occurs in the Baltic and on the west 

 coast of Sweden.» 



■»Skeletonema costatum (Grev.) Cl. rare. Occurs in the 

 spring and autumn in the plankton of the Skagerak, also in the 

 Baltic, to Aland, eise on the coasts of Iceiand, at the Shetlands, 

 in the North Sea, the English Channel and on the east of North 

 America.» 



»Chcetoceros bothnicus Cl. occurs very sparingly in the sample 

 from Baku. It inhabits the whole Baltic, especially the Bay of 

 Bothnia, and has been found at Spitzbergen and Iceland, also 

 in the summer along the west coast of Sweden.» 



»There occurs in the Baku-material another ChcBtoceros, 

 which seems to be new and for which I propose, provisionally 



Chcetoceros caspius Cl. 

 500 times magnified. 



the name C. caspius. It forms short, straight, not twisted chains 

 of quadrate cellules, which are so close, that there are no fora- 

 mina between them. The aAvns arise from the corners, are thin, 

 straight, apparently smooth and form with the longitudinal 

 axis an angle of about 45". The cell contents seem to have one 

 single chromatofore close to the wall of the connecting zone but 

 the material was not sufficiently well preserved for admitting of 



