MICROPLANKTON 215 



orders (Pennatae proper, if one prefers Schutt's system) as were found to occur tychopelagically in 

 these samples. Mainly meroplanktonic, neritic. 



Taxonomic notes 

 Changes in nomenclature of phytoplankton species have been adopted where recent taxonomic 

 research seems to justify them. Most of these are better known to plankton workers under earlier 

 names current in general handbooks such as Engler and Prantl's Pflanzenfamilien, the Nordisches 

 Plankton series and M. V. Lebour's Planktonic Diatoms of Northern Seas. It is hoped that these notes 

 may prevent further confusion. They give first the name used in this report in bold type, the best 

 known previous synonym, and then the authority for the change. Full synonymy is not attempted 

 here. Some brief comment has been offered concerning changes that still seem to the writer to be 

 of doubtful value, but detailed taxonomic study would require a separate report. (Where the first 

 person has been used in this section the opinions expressed are those held by one of us (T. J. H.) 

 personally.) 



Hemidiscus cuneiformis Wallich (i860), formerly Euodia cuneiformis (Wallich) or E. cuneiformis 

 Schiitt. 



Hustedt (1927-37, p. 903) and Hendey (1937, p. 264) have explained how the foundation of several 

 species that they believe to be but varieties or phases of the type, coupled with Castracane's error in 

 supposing that Euodia Bailey, 1861, predated Wallich's foundation of the genus Hemidiscus, has led to 

 prolonged uncertainty as to the correct naming of this species. It is interesting to note that in all the 

 welter of confusion Cleve (1901, p. 330) had worked back to the combination now considered correct, 

 although he later supported Gran's use of Euodia cuneiformis (Wallich) as synonymous with E. gibba 

 Bailey (Gran, 1905, p. 45). 



Actinoptychus senarius Ehrenberg, previously widely known as A. undulatus (Bailey). Hendey 

 (1937, pp. 271-2) shows that Ehrenberg's specific name should be adopted upon grounds of priority. 

 Confusion arose because Ehrenberg first described it as a species of Actinocyclus (Ehrenberg, 1838). 

 Later he himself recognized the structural differences that seemed to warrant the splitting of this 

 genus into Actinocyclus as most subsequent workers have known it, and Actinoptychus which he 

 established as a distinct genus, with A. senarius as the type-species (Ehrenberg, 1841, 1843). The 

 figures of this form given as an unnamed species of Actinocyclus by Bailey (1842) first received the 

 specific epithet undulatus from Kutzing (1844), and the combination Actinoptychus undulatus (Bailey) 

 was made by Ralfs in the fourth edition of Pritchard's History of the Infusoria, 1861 ! Ehrenberg him- 

 self seems to have had no doubt that the unnamed figure of Actinocyclus sp. given by Bailey, and later 

 called Actinocyclus undulatus by Kutzing, was specifically indentical with his own ' Actinocyclus ' (later 

 Actinoptychus) senarius (Ehrenberg, 1843, p. 328). 



Cerataulina pelagica (Cleve) Hendey comb, nov., more widely known as C. BergoniiH. Peragallo 

 or Cerataulus (Cerataulina) Bergonii (H. Peragallo). 



Hendey (1937, p. 279) states that though Peragallo first suggested the need for a new genus 

 (Cerataulina) when he described the species Cerataulus (Cerataulina) Bergonii H. Peragallo (1892), 

 he did not define that genus. Later it appears that Cleve (1894, p. 1 1) accepted Peragallo's tentatively 

 proposed name, while pointing out that the form which he had himself described earlier as Zygoceros 

 pelagicum (Cleve, 1889, p. 54) was a complete synonym. Yet the genus Cerataulina does not seem to 

 have been properly established anywhere until Schutt's publication of 1896 (in Engler and Prantl, 

 p. 95). Hendey's proposed combination seems the only means of bringing the species within the 

 bounds of accepted rules of nomenclature, though plankton workers have been familiar with 

 ' C. Bergonii ' for so long that they cannot but regret the change. 



