Titre :	British prosobranch and other operculate gastropod molluscs : keys and notes for the indentification of the species
Type de document :	texte imprimé
Auteurs :	Graham, Alastair, Auteur
Editeur :	The linnean society of londan
Année de publication :	1971
Importance :	112 p.
Format :	22 cm.
ISBN/ISSN/EAN :	978-0-12-294850-3
Langues :	Anglais (eng)
Index. décimale :	594 Mollusques
Résumé :	There are three keys on the following pages; one for animals found in marine habitats, the second for those met with in fresh water and a third for the two terrestrial operculate gastropods found in Britain. Estuarine animals may be identified predominantly by way of the marine key, but many can be run down from the freshwater one, so that it is hoped that the fact that there is no hard and fast line separating brackish and truly freshwater habitats may be overcome. Each key leads to the identification of the family to which the specimen belongs and a reference to the page on which that family is dealt with. Here important familial characters are summarized and further keys, if required, lead to the identification of, first, the genus and then the species to which the specimen belongs. Lastly, a few notes on each species are given. These include its broad distribution in this country and the height of the shell in millimeters, except in the case of limpets, where the measurement refers to the anteroposterior length. In most cases I have tried to use the true generic and specific characters in the keys except where these are based on internal features, since my aim has been to allow identification on external features and leave the animal alive and intact for further work. The use of critical specific features has not always been possible, and in some groups (e.g. pyramidellids, which are notoriously difficult to identify; and reside) recourse has to be had to probably unimportant details. For this reason drawings are given of most shells, since it is too difficult a task to try to describe in words the elaborate three dimensional shape of the gastropod shell. In most cases shells are drawn with the apex upwards and the mouth towards the observer. dimensional shape of the gastropod shell. In most cases shells are drawn with the apex upwards and the mouth towards the observer.

British prosobranch and other operculate gastropod molluscs : keys and notes for the indentification of the species [texte imprimé] / Graham, Alastair, Auteur . - The linnean society of londan, 1971 . - 112 p. ; 22 cm.
ISBN : 978-0-12-294850-3
Langues : Anglais (eng)

Index. décimale :

594 Mollusques

Résumé :

There are three keys on the following pages; one for animals found in marine habitats, the second for those met with in fresh water and a third for the two terrestrial operculate gastropods found in Britain. Estuarine animals may be identified predominantly by way of the marine key, but many can be run down from the freshwater one, so that it is hoped that the fact that there is no hard and fast line separating brackish and truly freshwater habitats may be overcome. Each key leads to the identification of the family to which the specimen belongs and a reference to the page on which that family is dealt with. Here important familial characters are summarized and further keys, if required, lead to the identification of, first, the genus and then the species to which the specimen belongs. Lastly, a few notes on each species are given. These include its broad distribution in this country and the height of the shell in millimeters, except in the case of limpets, where the measurement refers to the anteroposterior length. In most cases I have tried to use the true generic and specific characters in the keys except where these are based on internal features, since my aim has been to allow identification on external features and leave the animal alive and intact for further work. The use of critical specific features has not always been possible, and in some groups (e.g. pyramidellids, which are notoriously difficult to identify; and reside) recourse has to be had to probably unimportant details. For this reason drawings are given of most shells, since it is too difficult a task to try to describe in words the elaborate three dimensional shape of the gastropod shell. In most cases shells are drawn with the apex upwards and the mouth towards the observer. dimensional shape of the gastropod shell. In most cases shells are drawn with the apex upwards and the mouth towards the observer.