. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 194 ANNALS OF THE SOUTH AFRICAN MUSEUM posterior part of the furrow is especially deep and clear-cut. It seems very probable that the furrow served to transmit the duct of Jacobson's organ. Camp & Wells (1956) found a similar groove leading from a depression in the snout of Placerias and mentioned the possibility of this being evidence for the presence of Jacobson's organ. Pearson (1924) also found indications of the organ in Kannemeyeria. In a sectioned dicynodont ( 10081) a similar groove
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 194 ANNALS OF THE SOUTH AFRICAN MUSEUM posterior part of the furrow is especially deep and clear-cut. It seems very probable that the furrow served to transmit the duct of Jacobson's organ. Camp & Wells (1956) found a similar groove leading from a depression in the snout of Placerias and mentioned the possibility of this being evidence for the presence of Jacobson's organ. Pearson (1924) also found indications of the organ in Kannemeyeria. In a sectioned dicynodont ( 10081) a similar groove opening into the anterior choanal notch was found alongside the pre- maxillary septum. In recent reptiles the duct of Jacobson's organ opens into the anterior part of the choana, and in mammals, where the primitive choana has been eliminated by the secondary palate, it passes into the oral cavity through the naso-palatine foramen (foramen incisivum) which lies between the premaxilla and maxilla (Goodrich, 1930; Stadtmiiller, 1936). This reconstruction of the duct of Jacobson's organ in Lystrosaurus is at variance with Brink's (i960) deductions regarding the septomaxillary region of a sectioned therocephalian, Akidnognathus parvus. Brink, in the first place, maintained that the morphology of this region in therocephalians is different from that of the same region in dicynodonts, but comparison of Figures 29 and 32 with Brink's (i960) Figure 36 shows that the two regions are essentially similar in Akidnognathus and Fig. 30. Lystrosaurus sp. No. \'entral view of inner frontal and nasal 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
