. Journal of anatomy. y the nasal mucoussac. It may be followed out in all its stages in Dasyurus viverrinus. At the7-mm. stage it is non-existent; by the 9-5-mm. stage it has just begun toform in the way mentioned; and by the 25-mm. stage, so far has the 340 Professor Edward Fawcett posterior wall of the nasal capsule been pushed back that a large triangularlamina transversalis posterior results, and its medial basal angle, which haspreviously fused with the hinder-pointed end of the anterior paraseptalcartilage, is drawn out to form the slender posterior part of the resultingcounnon parasept
. Journal of anatomy. y the nasal mucoussac. It may be followed out in all its stages in Dasyurus viverrinus. At the7-mm. stage it is non-existent; by the 9-5-mm. stage it has just begun toform in the way mentioned; and by the 25-mm. stage, so far has the 340 Professor Edward Fawcett posterior wall of the nasal capsule been pushed back that a large triangularlamina transversalis posterior results, and its medial basal angle, which haspreviously fused with the hinder-pointed end of the anterior paraseptalcartilage, is drawn out to form the slender posterior part of the resultingcounnon paraseptal cartilage. In all the orders and species I havepersonally examined and modelled, a lamina transversalis posterior exists,although not in the very young stages. It is a comparatively late forma-tion. Its presence is generally denied in Primates and man, but in a modelof the chondrocranium of a 65-mm. embryo in my possession a small laminatransversalis posterior is distinctly present, and it is formed precisely as in. Tkxt-fig. 4.—The evolution of the paraseptal cartilages and the laminatransversalis posterior (schematic). A. Tlie V-mii). stage in Dasyurus viverrinus. B. The 9-mm. stage in Dasyurus viverriinis. and in rahbit, water-rat, Trichosurus. C. Talpa. D. Ferret, cat. E. ilan. 1, 4, interorbito-uasal septum ; 2, anterior paraseptal cartilage ; 3, part wliich, bythrusting back and hollowing out, forms posterior paraseptal cartilage, laminatransversalis posterior, and cupula posterior; 5, lamina transversalisanterior ; 6, crista semicircularis ; 7, first primary ethnio-turbinal ; S, laminatransversalis posterior ; 9, p isterior paraseptal cartilage ; 10, fibrous internalcovering of common paraseptal cartilage jiersisting after disappearance ofcartilage itself ; 11, cupula posterior. other animals. In the schemes illustrated by fig. -i the various forms areshown. « The Medial Aspect of the Lateral Wall of the A^asal Capsule (PI. 10).—This, like the lateral aspect, is
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
