Walter Pupinj. 249 



nature the menobranchus occupy nearly the lowest place among 

 Amphibians, which class stands between fish and reptiles. Physi- 

 ologically they are fish having legs in place of fins, if such a 

 monstrosity could be admitted in fish aristocracy ! They cannot 

 live out of water as long as some other fish, for the reason that 

 the gills are exposed and dry more readily in consequence. If 

 the body is kept moist life is sustained for a greater length of 

 time, proving that aeration is, to a slight degree, carried on 

 through the skin. 



It is an interesting fact that the early tadpole stage of salaman- 

 ders resemble the adult menobrach. In early life the Amblis- 

 toma lurida — the life history of which I have carefully studied — 

 is strictly aquatic, has a tricamerate heart and rudimentary lungs. 

 However, when the legs and feet are b?ing developed the gills 

 begin to wither and the lungs to assume functional duty, imper- 

 fect as yet though it may be. The second auricle to the heart is 

 now being developed in^ this transition stage. In this condition 

 the young sala'mander has been considered a privileged animal — 

 that while in water branchial respiration was sufficient, and again, 

 "when on land pulmonary respiration was all sufficient — a per- 

 fectly amphibious animal. But we may withhold our admiration 

 of this privileged condition, for in fact it cannot live in, or out, 

 of water, the gills being partly absorbed, while the yet imper- 

 fectly developed lungs render aerial respiration quite imperfect. 

 So the poor animal has to come to the surface for a mouthful of 

 air and plunge back into the water in order thus to secure the full 

 benefit of the imperfect gills; so they have to play at shuttlecock 

 from one element to the other, not being able to live in either ele- 

 ment alone. I am persuaded that the central organ of the circu- 

 lation (the heart) indicates the mode of respiration, as no air- 

 breathing vertebrate has less than three chambers in the heart, 

 and no aquatic vertebrate has more than a two-chambered heart. 

 Now as the menobranch cannot live out of water— is strictly 

 aquatic — has only branchial respiration — reason sufficient to 

 prove that they are provided with a bicamerate heart. On dis- 

 section we found the two-chambered heart, as anticipated. In 

 studying the salalemanon I found when a leg was amputated it 



