. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. CR.\NIAL MORPHOLOGY OF THE DICYNODONT GENUS LTSTROSAURUS 197. Fig. 32. Lystrosaurus declivis. No. Interior of snout in medial view. Reconstructed from serial sections. donts, however, the duct enters the nasal cavity dorsally and anteriorly to the maxillary antrum, making it unlikely that the course postulated by Kemp was followed in these animals. Moreover, the close association between the naso- lacrimal duct and septomaxilla in Dasypus (Fuchs, 1911) suggests that the duct in theraps
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. CR.\NIAL MORPHOLOGY OF THE DICYNODONT GENUS LTSTROSAURUS 197. Fig. 32. Lystrosaurus declivis. No. Interior of snout in medial view. Reconstructed from serial sections. donts, however, the duct enters the nasal cavity dorsally and anteriorly to the maxillary antrum, making it unlikely that the course postulated by Kemp was followed in these animals. Moreover, the close association between the naso- lacrimal duct and septomaxilla in Dasypus (Fuchs, 1911) suggests that the duct in therapsids other than Lystrosaurus passed through, or close to, the septomaxilla. The smaller septomaxillary foramen, between the septomaxilla and maxilla, in this case probably served to transmit the duct of the lateral nasal gland, which in recent reptiles opens into the vestibule at this point (Pratt, 1948) and serves to moisten the nostril. The septomaxillary foramen is a feature of the Gorgonopsia, Therocephalia and Dinocephalia (Boonstra, 1934a, 1934^, 1968). In the Squamata, the septomaxilla has abandoned its primary position as a surface bone of the snout and migrated medially to form a roof for Jacob- son's organ, and loses its association with the duct of the lateral nasal gland. Laterally the nasal cavity leads to an extensive maxillary antrum, which surrounds the root of the tusk in the base of the zygomatic arch (Figs 29, 32, 33, 35: MAX. ANT.). Anteriorly the antrum is bounded by the maxilla and lacrimal, and laterally and posteriorly by the jugal. Dorsally the antrum leads into two blind pouches, one reaching forward to near the lacrimal canal, and. 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 South African Museum. Cape Town : The Museum
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
