. The American journal of anatomy . above indicate,Bremer regards the reptilian lung as possessing a bilateraleparterial system and differentiating in this regard from themammalian types. Both of these assumptions are mammalian genera and species are now known to havetypically a bilaterally symmetrical eparterial bronchial organi-zation. Others show in individuals in addition to the normalright eparterial bronchus a corresponding derivative from theleft stembronchus as a variant acquisition. In both groups theeparterial components are distinct mammalian neomorph de-velopments an
. The American journal of anatomy . above indicate,Bremer regards the reptilian lung as possessing a bilateraleparterial system and differentiating in this regard from themammalian types. Both of these assumptions are mammalian genera and species are now known to havetypically a bilaterally symmetrical eparterial bronchial organi-zation. Others show in individuals in addition to the normalright eparterial bronchus a corresponding derivative from theleft stembronchus as a variant acquisition. In both groups theeparterial components are distinct mammalian neomorph de-velopments and not reappearances of an archeal reptilian-char-acter. The assumption that the modern reptiles possess a 112 GEO. S. HUNTINGTON symmetrical cparterial unfolding in both lungs is based on thevery few prophetic remarks with which Aeby (2) concludes hismain work on the mammalian bronchial tree. He there (p. 96)merely expresses the expectation that the contrast between theeparterial and hyparterial bronchial derivatives determined by. Fig. 3 Aspidonectes spinifcr, Le Sueur. Corrosion of right lung and pul-monary artery. Ventral view. Columbia Morph. Mus., no. 1931. him for the mammalia would be found in the reptilia representedby a transition into parallel longitudinal rows of bronchi,placed on the medial and lateral side of the pulmonary suggestions along this line he considers unwarranted inview of his lack of material. Zumstein, one of the earliest investigators to analyze Aebysview critically, reported (39) on several reptilian lung corro- PULMONARY EVOLUTION IN MAMMALIA 113 sions. In one marine chelonian of undetermined genus he de-scribes the pulmonary artery as crossing the stembronchus highup, before any lateral bronchi arise, and continuing caudad onits dorso-lateral aspect, giving branches from each side to thebronchial derivatives. The distribution of the tree is thereforeentirely hyparterial. Hesser (22), as quoted from a personalcommunication by Flint (
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