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Registros recuperados: 51 | |
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Pafort-van Iersel, Trudy; Spoel, S. van der. |
The phylogenetic relation between Clio pyramidata Linnaeus, 1767, and Cymbulia peroni De Blainville, 1818, has been studied with regard to the structure of their muscle systems. Specimens of both species collected from the North Atlantic Ocean and the Mediterranean were sectioned 5 µm thick and stained with Haematoxilin-Eosin, Crossmon or Azan for histological purposes or they were studied as cleared dissected or entire animals. The columellar muscle and subectodermal wing muscles of both species are described. It is concluded that Clio shows neoteny since it develops without metamorphosis. The asymmetry in anatomy proves that both Clio and Cymbulia descend from spiralised ancestors. For Clio two primitive characters are discussed which may be due to the... |
Tipo: Article / Letter to the editor |
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Ano: 1979 |
URL: http://www.repository.naturalis.nl/record/504496 |
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Spoel, S. van der. |
The columellar muscle system consists anteriorly of a high number of longitudinal branches surrounding a hydrocoel, which forms higher up two lateral, one ventral and four smaller dorsal bundles. These bundles enter the muscular envelope of head and nuchal region, which is formed out of the wing-wall muscles. The two lateral bundles proceed farest apically to insert on the buccal appendages; the four dorsal fibres fuse with the walls of buccal organs and oesophagus, while the ventral muscles run into the posterior and lateral footlobes. The wings are attached to the body by an extra right and left muscle neither derived from the columellar nor from the wing-wall muscle system. So the posterior and lateral footparts are mesopodal, the wings epipodal and the... |
Tipo: Article / Letter to the editor |
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Ano: 1982 |
URL: http://www.repository.naturalis.nl/record/505289 |
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Spoel, S. van der. |
The occurrence of aberrant stages in the protandric hermaphrodite Clio pyramidata is considered in relation to the sexual cycle of this species. The anatomy of the juveniles, males and females is shortly discussed especially with regard to their sexual organs. The anatomy of the developing (the normal-complete) and of the growingaberrant stage is briefly reviewed. It is shown that the aberrant stage is formed by strobilation of a normal specimen, probably as a result of less favourable environmental conditions. As the most important conclusions it can be stated that: 1) the aberrant stage described by van der Spoel (1962) is a normal stage in the life cycle; 2) the aberrants are most abundant in the population in the months before the reproductive peaks;... |
Tipo: Article / Letter to the editor |
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Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/504282 |
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Spoel, S. van der. |
A new method for the use of infraspecific variation in the characterization of watermasses in the past is indicated. The various formae of the thecosomatous pteropod Clio pyramidata can be distinguished by the size of their protoconch. Since in marine sediments these protoconchae are usually the most intact part of the pteropod shells, they can be used to trace the distribution of the formae in the past, and thus of the watermasses of which these are characteristic. |
Tipo: Article / Letter to the editor |
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Ano: 1975 |
URL: http://www.repository.naturalis.nl/record/505468 |
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Spoel, S. van der. |
Part of the “Thor” collections are studied, with the aid of notes by Dr. J.J. Tesch. A new species, Pneumodermopsis (Pn.) teschi, is described, and the variability of some taxonomic characters in Thliptodon are mentioned. A distributional map for the “Thor” records, based on material from the collection of the Zoological Museum in Copenhagen and on the notes left by Tesch, is provided. |
Tipo: Article / Letter to the editor |
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Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/505400 |
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Spoel, S. van der. |
The protoconch in Limacina helicoides, Peraclis moluccensis, Styliola subula, Cavolinia globulosa, C. gibbosa, C. inflexa and C. longirostris are described; finer structures of the shell in these species and Hyalocylis striata, Diacra quadridentata and Cavolinia tridentata are described. The occurrence of a distinct protoconch-I and -II in Cavoliniidae is discussed as well as the taxonomic value of the structure of the ventral ribs in the Cavoliniidae mentioned. |
Tipo: Article / Letter to the editor |
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Ano: 1976 |
URL: http://www.repository.naturalis.nl/record/505087 |
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Spoel, S. van der. |
A number of samples collected by the Scotia and Explorer Expeditions in 1950 in the North Atlantic were found among undetermined material left by Dr. J. J. TESCH after his death in 1954. Some interesting specimens in these samples seem to justify their publication. My grateful acknowledgements are tendered to Dr. J. H. FRASER of the Marine Laboratory at Aberdeen, for so kindly giving me full information concerning the samples. The author is also very much indebted to Dr. C. O. VAN REGTEREN ALTENA who lent the material of both expeditions, which is part of the collection of the Leiden Museum. Table I gives an enumeration of the species met with and the data concerning the stations. In Fig. 1 the stations are given together with surface currents. |
Tipo: Article / Letter to the editor |
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Ano: 1964 |
URL: http://www.repository.naturalis.nl/record/505116 |
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Spoel, S. van der. |
The technical details and hydrographie data of the hauls with open nets and opening-closing nets made during the Amsterdam Mid North Atlantic Plankton Expeditions (AMNAPE) in 1982 and 1983 are given together with the general conditions during the sampling periods: 1-27 February 1982 and 27 May – 24 June 1983. Temperature and salinity profiles and correlations are given for the sampled area roughly between 55°N 30°W and 24°N 30°W. |
Tipo: Article / Letter to the editor |
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Ano: 1985 |
URL: http://www.repository.naturalis.nl/record/505539 |
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Spoel, S. van der. |
The pelagic fauna of the Red Sea shows special variation induced by its isolated character (Van der Spoel, 1971). Clio pyramidata from the Red Sea is usually incorrectly referred to as the tropical forma lanceolata (Lesueur, 1813) or the typical forma pyramidata Linnaeus, 1767. Some large samples with C. pyramidata from the northern Red Sea made it possible to establish the correct identity of these populations. Though special variation, like described for Diacria and Cavolinia species (Van der Spoel, l.c.), is found for Red Sea populations of C. pyramidata, the populations are not separated as an endemic taxon as the specimens resemble closely Clio pyramidata forma convexa (Boas, 1886) (figs. 1-4). The anterior parts are almost identical to those of... |
Tipo: Article / Letter to the editor |
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Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/505325 |
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Spoel, S. van der. |
Two subspecies new to science: Diacria quadridentata erythra and Cavolinia uncinata pulsatapusilla are described from the Red Sea. The formae: D.q. quadridentata forma schmidti, D.q. erythra forma erythra, D.q.e. forma crassa, C. longirostris forma flexipes, C. uncinata pulsalapusilla forma pulsatapusilla and C.u.p. forma pulsatoides new to science are described from the Pacific Ocean and Red Sea. |
Tipo: Article / Letter to the editor |
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Ano: 1971 |
URL: http://www.repository.naturalis.nl/record/504961 |
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Spoel, S. van der. |
The mid North Atlantic between 24°N and 55°N along 30°W and between 20°W and 30°W along approx. 25°N, investigated by the AMNAPE cruises in the four seasons, spring (1980), summer (1983) autumn (1981) and winter (1982), is dominated by Temperate waters with a northern and southern branch of the North Atlantic Drift, Subtropical Sargasso Sea waters in the south and Subarctic waters in the north (Yen der Spoel, 1981, 1986; Van der Spoel & Meerding 1983; Pafort- van Iersel, 1985). The present study gives the relation of the microplankton distribution in the upper 5m of the water column with the hydrography and seasons. |
Tipo: Article / Letter to the editor |
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Ano: 1987 |
URL: http://www.repository.naturalis.nl/record/506328 |
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Spoel, S. van der. |
INTRODUCTION Specimens of Heteropoda, especially of Atlantidae, which are damaged by the nets and have lost their shells by the action of preservatives are usually considered to be hardly identifiable. Tokioka (1961) used the opercula as a new source of morphological information for the study of the shell-less Atlantidae. The laborious preparation of opercula enables only the identification of some species. The occurrence of groups of closely related taxa showing only slight morphological differences is responsible for other difficulties in identification. Recent expeditions, like the Cicar Expedition, the Eastropac Expeditions and the Acre project provided samples with large quantities of damaged heteropods, which induced me to look for a simple method to... |
Tipo: Article / Letter to the editor |
Palavras-chave: 42.73. |
Ano: 1972 |
URL: http://www.repository.naturalis.nl/record/319387 |
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Dresscher, Th.G.N.; Engel, H.; Spoel, S. van der. |
Es wird Xerobdella-Material aus 11 neuen Fundorten in Jugoslawien erwähnt. Wir wissen leider noch nicht genug über die Variabilität der beiden Xerobdella-Arten (X. lecomtei und X. anulata) um mit Sicherheit sagen zu können ob hier zwei Arten oder zwei Subspecies einer Art vorliegen. Je mehr Exemplare bekannt werden, desto grösser erscheint die Variabilität. Es ist nicht sicher ob wirklich bei allen als X. lecomtei beschriebenen Tieren genau die Zahl der Ringe zwischen den Genitalöffnungen gezählt worden ist. Unsere Exemplare zeigen 4 bis 5 Ringe, während Autrum nur 4½ Ringe für X. anulata angab, dagegen 3 bis 3½ Ringe für X. lecomtei. Vorläufig nennen wir unsere Tiere darum Xerobdella anulata Autrum, 1958, die vermutlich südlich der Julischen Alpen vorkomme. |
Tipo: Article / Letter to the editor |
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Ano: 1966 |
URL: http://www.repository.naturalis.nl/record/505169 |
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Registros recuperados: 51 | |
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