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| Graaf, Fr. de. |
| While studying the plankton community of the “Loenerveense Polder”, one of the lakes along the eastern bank of the river Vecht, I came across an unusually large form of the genus Hyalosphenia. The species occurred in a qualitative net sample taken from the open water. Only one living specimen and two empty thecae were then observed. Though numerous net samples were taken from the same locality throughout the year, I did not meet with the animal again, only empty thecae sometimes being found. However when for the purpose of recovering more specimens, samples of bottom mud were taken, the living animal was seen again, though only once, and in one living specimen. After that I did not succeed in catching the animal again. Describing a new species from such... |
| Tipo: Article / Letter to the editor |
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| Ano: 1952 |
URL: http://www.repository.naturalis.nl/record/505115 |
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| Graaf, Fr. de. |
| For the last twenty years several authors have been pointing out, that the species of the genus Lepas are very difficult to distinguish. The forms Lepas anatifera Linné and Lepas anserifera Linné especially cause trouble in identifying. It is often hard and sometimes even impossible to distinguish them by an examination of the shell pieces alone. The only distinguishing mark between the two species is the number of the filamentary appendages, which is two (seldom only one) for Lepas anatifera and four to six for Lepas anserifera. The other characters of the capituium used in most of the earlier keys are too variable to be used for accurate identifying. The number of the filamentary appendages may render good service too if one has to distinguish Lepas... |
| Tipo: Article / Letter to the editor |
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| Ano: 1952 |
URL: http://www.repository.naturalis.nl/record/504923 |
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