650 DR. A. WILLEY ON THE RESPIRATORY 



bulges conspicviously downwards and backwards so that the 

 greatest convexity lies behind, at the base of the throat. 

 Presumably, in this act of dilation, the glottis is opened ; and, in 

 fact, Cryptobrmiclms seems to show some increase of girth after 

 inhalation. 



Inhalation through the nostrils was observed by G. B. Wilder 

 in a Japanese CryptohrancliiLS, 2| feet long, which he kept in 

 shallow water sufficient to cover it *. The downward protrusion 

 of the floor of the mouth in narial inspiration, the arching of the 

 back, and the swaying movement at the bottom have been 

 described by A. M. Heese t, who adds that the hellbender will 

 survive more than a week's exposure out of water without 

 suffering any permanent diminution of vitality. The longest time 

 that any individual Avas observed by him to remain under water 

 was 43 minutes. B. G. Smith t confirmed the observation that 

 the arching of the back is a sign that air has entered the lungs. 

 No writer seems to have reported the extraordinary yawning 

 under water to which I have alluded. 



Another equally deep tank held at least a dozen examples of 

 Necturus. On both occasions they remained undisturbed at the 

 bottom of the aquarium without betraying any signs of unusual 

 activity such as would attend recent or approaching visits to the 

 surface. Some of them had lived for three years in the aquarium ; 

 their bodies were sleek, firmly rounded, and fully extended. 



There is a point concerning the vascular system which requires 

 slight emendation. All the blood that leaves the heart of 

 Necturus passes through the afTerent branchial arteries to the 

 external gills. J. E. Y. Boas (Morph. Jahrb. vii. 1882) had 

 described an external carotid artery arising from the first afferent 

 artery on each side, between the heart and the base of the first 

 gill. I have satisfied myself by injection that this artery does 

 not exist in the position claimed for it by Boas. It arises from 

 the first efferent artery as described and figured by W. S. Miller §. 



Unfortunately, two papers by H. L. Bruner had escaped my 

 notice earlier |!. In these i-egular oscillations cf the floor of tiie 

 mouth in aquatic respiration are attributed to Necturus, and, 

 under certain experimental conditions, of which temperature is 

 one of the factoi'S, pulmonary respiration is stated to occur at in- 

 tervals. Bruner's analysis of the respiratory movements observed 



* Burt G. Wilder : "0\\t\\e\\AV\ts,o(CryptohraHclius." Amer.Nat. xvi. pp. 816- 

 817, 1882. 



t Albert M. Reese: "The habits of the Giant Salamander." Pop. Science 

 Monthly, vol. Ixii. pp. 526-531. "New York, 1903. 



X Bertram G. Smith : " The life-history and habits of Cri/ptobranclms allec/heni- 

 ensls." Biol. Ball. xiii. pp. 5-39, 1907. 



§ W. S. Miller : " The vascular system of Necturus maculattts." Contributions 

 from the Anatomical Laboratory of the University of Wisconsin, ]3ull. Univ. 

 Wisconsin, No. 33, Science Series, vol. ii. No. 3, pp. 211-226, pis. ix.-xi. Madison, 

 Wisconsin, 1900. 



II H. L. Bruner: 1. "The Mechanism of Pulmonary Respiration in Amphibians 

 with Gill-Clefts." Morph. Jahrb. xlviii. pp. 63-82, 1914. 2. " Jacobson's Organ and 

 the Respiratory Mechanism of Amphibians." Ibid. pp. 157-165. 



