. Bulletin of the British Museum (Natural History), Geology. NORTHERN SHAN STATES, BURMA 141 while the adjoining inner spaces become narrow and groove-like. It appears that the ventral tongue fits inside the extremities of the dorsal costae. Order SPIRIFERIDA Suborder ATHYRIDOIDEA Superfamily ATHYRIDACEA M'Coy 1844 Family ATHYRIDIDAE M'Coy 1844 Subfamily ATHYRIDINAE M'Coy 1844 Genus ATHYRIS M'Coy 1844 Type species. Terebratula concentrica von Buch 1834 : I23- Athyris sp. (PI. 7, figs. 1-5; Text-fig. 5) 1908 Athyris concentrica Reed : no, pi. 16, figs. 18, 19. Material. Twenty specimens. Figure
. Bulletin of the British Museum (Natural History), Geology. NORTHERN SHAN STATES, BURMA 141 while the adjoining inner spaces become narrow and groove-like. It appears that the ventral tongue fits inside the extremities of the dorsal costae. Order SPIRIFERIDA Suborder ATHYRIDOIDEA Superfamily ATHYRIDACEA M'Coy 1844 Family ATHYRIDIDAE M'Coy 1844 Subfamily ATHYRIDINAE M'Coy 1844 Genus ATHYRIS M'Coy 1844 Type species. Terebratula concentrica von Buch 1834 : I23- Athyris sp. (PI. 7, figs. 1-5; Text-fig. 5) 1908 Athyris concentrica Reed : no, pi. 16, figs. 18, 19. Material. Twenty specimens. Figured specimens. BB 55559, BB 55589D. Description. Exterior. In outline the shells are rhomboidal and in lateral profile they are subequally biconvex. The pedicle valve bears a prominent pointed incurved ventral beak and a short, curved hinge line equal to about half the maximum width which is met near midlength. Width and length commonly are approximately equal. The ventral beak is pierced by a large circular foramen joining a broad, low, triangular delthyrium anteriorly. Most of the delthyrium is filled with the beak of the brachial valve. The pedicle valve bears a broad, shallow sulcus and the brachial valve bears a faintly developed fold which manifests itself in some shells as a faintly subcarinate form. The exterior is covered by numerous lamellose concentric growth lines. u O B-12 80 Fig. 5. Athyris sp., serial sections of BB 55589D x 5 (sections A, B) and X 6 (section C). Numbers indicate distance in millimeters from the anterior. Original length was 14-70 mm. Interior structures. The pedicle valve bears short dental lamellae set close to the lateral margins of the interior. The brachial valve bears a flat cardinal plate with a. 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 Mus
Size: 1460px × 1712px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
