. Bulletin of the British Museum (Natural History), Geology. 302 CRETACEOUS CYCLOTHYRIS. Fig. 4. A series of fifteen transverse serial sections through the umbo of a dupHcate specimen of CyclothyHs densleonis Anderson from the Horsetown Group (Albian-Ceno- manian), Shasta County, Cahfornia. Geological Survey of America Locality No. 1051. The encircling deltidial plates around the foramen, the comparatively short dental lamellae and general morphology of the hinge-plates are typical of the genus. The numerals denote the distance in millimetres between each section, x 3. SYSTEMATIC DESCRIPTION F
. Bulletin of the British Museum (Natural History), Geology. 302 CRETACEOUS CYCLOTHYRIS. Fig. 4. A series of fifteen transverse serial sections through the umbo of a dupHcate specimen of CyclothyHs densleonis Anderson from the Horsetown Group (Albian-Ceno- manian), Shasta County, Cahfornia. Geological Survey of America Locality No. 1051. The encircling deltidial plates around the foramen, the comparatively short dental lamellae and general morphology of the hinge-plates are typical of the genus. The numerals denote the distance in millimetres between each section, x 3. SYSTEMATIC DESCRIPTION Family RHYNGHONELLIDAE Gray 1848 Subfamily CYGLOTHYRIDINAE Makridin 1955 Genus CYCLOTHYRIS M'Coy 1844 CyclothyHs densleonis (Anderson) Fig. 4 ; PI. 5, figs 1-6 1902 Rhynchonella densleonis Anderson 1958 Rhynchonella densleonis Anderson Description. External characters. Acutely biconvex Cyclothyris, 17-2 mm long, 20 mm wide, 11-9 mm thick. Broadly triangular in general outline. The brachial 72 ; pi. 7, figs 157, 158. Anderson : 86 ; pi. i, figs 3,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
Size: 1656px × 1509px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
