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University of California Publications in Zoology [Vol. 16 



It is the general experience that pelagic protozoa are cosmopolitan 

 and are found widely and quite generally in large numbers. There 

 are, to be sure, espeeiall.y among the highly differentiated and minute 

 dinoflagellates of the family Dinophysidae, not a few instances in which 

 only a very few individuals of a species have ever been .seen. This 

 may be due to escape through the meshes of the silk net on the one 

 hand and thus not necessarily to rarity in nature, or on the other to 

 actual rarity which is not unknown in nature among highly specialized 

 tropical species of plants and animals, as among orchids, birds of 

 paradise, and species of cowries (Cypraea) . 

 A classic instance in recent literature of a 

 persistently rare species is Oenothera la- 

 marckiana, and other cases are not unknown 

 among fresh- water rotifers. However, in 

 the case of Dictyocysta the genus is not 

 extremely specialized and the other species 

 are all fairly abundant and of wide distri- 

 bution in all warm or temperate seas. The 

 occurrence of a rare species in this genus 

 is therefore to be looked upon with suspi- 

 cion and some other explanation than rarity 

 in nature sought for absence of records of 

 its reappearance. 



Brandt (1907) in his monograph of the 

 Tintinnoina of the Plankton Expedition 

 reduces Haeekel's species to Dictyocysta 

 templum var. tiara with the comment : 

 "Ich halte D. tiara nur fiir eine allerdings 

 sehr sonderbare Formvarietiit von D. templum und bezweifle, dass die 

 Figur richtig ist. Sie gehort wohl — wie manche der anderen von 

 Haeckel selbst gezeichneteu Abbildungen — zu den 'Kunstformen der 

 Natur. ' " The last reference is to the well-known art work in which 

 Haeckel has assembled and portrayed, not always with scientific accu- 

 racy, the beautiful and bizarre forms of life, including many from the 

 pelagic organisms of the sea. 



The opportunity which my investigations of the past fifteen years 

 have given me of becoming acquainted with micro-organisms of the 

 pelagic life of the sea under various conditions, and especially my 

 contact with the Tintinnoina, has brought that experience which enables 

 the investigator to detect the abnormal from the normal, or at least 



Fig 1. Dictyocysta tiara 

 Haeckel. X 500 After 

 Haeckel (1873, pl.27, fig.7). 



