Annales du Musée de l'Afrique du Sud  = Annale van die Suid-Afrikaanse Museum . B Fig. 253. (Delawarella Menabites) sp. aff. jeanneti s.l. Collignon, 1948. SAMPCZ5691. X 0,85. Les faunes du Crétacé supérieur d'AFRIQUE DU SUD 333 et allongée vers l'intérieur. fortement point Avec l'augmentation du diamètre côtelé et remainsweak avec prorsiradiate latérale à peine perceptible (2) et (3),submarginale et légèrement plus fort marginal (4), mais progressivement plus forte andexternal ombilicale (1) (5) des tubercules. De nombreuses intercalations babyloniennes et les bifurcations, generallyat le site de l'bacille submarginale, mais aussi parfois à la

• Contributeur: The Reading Room / Alamy Banque D'Images
• ID de l’image: 2AJ3B08
• Taille du fichier: 7,1 MB (559,4 KB Téléchargement compressé)
• Autorisations: Modèle - non | Propriété - non
• Dimensions: 1579 x 1582 px | 26,7 x 26,8 cm | 10,5 x 10,5 inches | 150dpi

Informations supplémentaires

Cette image appartient au domaine public, ce qui signifie que le droit d’auteur a expiré ou que le titulaire du droit d’auteur a renoncé à ses droits. Les frais facturés par Alamy couvrent l’accès à la copie haute résolution de l’image.

Cette image peut avoir des imperfections car il s’agit d’une image historique ou de reportage.

Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum . B Fig. 253. Menabites (Delawarella) sp. aff. jeanneti s.l. Collignon, 1948. SAM~PCZ5691. X 0, 85. CRETACEOUS FAUNAS FROM SOUTH AFRICA 333 elongated and point strongly inward. With increasing diameter ribbing remainsweak and prorsiradiate with barely perceptible lateral (2) and submarginal (3), and slightly stronger marginal (4), but progressively stronger umbilical (1) andexternal (5) tubercles. Numerous intercalations and bifurcations occur, generallyat the site of the submarginal tubercle, but also occasionally at the umbilicaltubercle. This results in there being about twice as many external as internaltubercles. Specimen SAM-PCZ5691 (Figs 252-253) has part of the early bodychamber preserved. Here tuberculation weakens even more, and the ribsbecome wider spaced. The suture is only partially exposed in the present material. The keel, asfar as can be seen, is never very prominent.. Fig. 254. Menabites (Delawarella) sp. aff. jeanneti s.l. Collignon, 1948. SAM-FB. x 1. 334 ANNALS OF THE SOUTH AFRICAN MUSEUM Discussion This species is identified by the fine, dense ribbing throughout, and thevery poor development of the lateral and submarginal tubercles. Collignon (1948: 34-36), in erecting M. {D.)Jeanneti, distinguished betweena typical form and a more compressed form, var. compressa, the difference inwhorl breadth between the two forms being approximately 5 per cent. Thelarger Zululand specimen, SAM-PCZ5691 (Figs 252-253), with a whorl breadthof 39 per cent of the diameter, appears closer to the typical form of M. (D.)jeanneti than to the compressed variety. The main difference between the Zulu-land material and the Malagasy specimens of M. (D.) jeanneti, lies in the factthat, in the adult stage, the latter lose ornament on the venter and take on theappearance of a pachydiscid. In the Zululand specimens the venter remains

Recherche dans la banque de photos par tags

• bookcentury1800
• bookdecade1890
• booki
• booksubjectnaturalhistory