LIFE HISTORY OF DESMOGNATHUS FUSCA. 325 



No. 9. Two small beetles, a dipterous insect, a 

 small green caterpillar, and an insect 

 larva. 



No. 10. Remains of an aquatic insect larva. 

 No. II. Sand, dirt, and unrecognizable debris. 

 No. 12. A small annelid, fragments of a larger 

 annelid, two small crustaceans (prob- 

 ably Gammarus], some mites, and frag- 

 ments of adult insects. 



No. 13. An adult dipterous insect, fragments of 

 other small insects, some very minute 

 mites, and unrecognizable debris. 

 No. 14. A small mite. 

 No. 15. A whole Desmognathus larva. 

 No. 16. A whole Desmognathus larva. 

 No. 17. Moulted skin of Desmognathus. 

 No. 18. An earthworm, a small spider, and some 



six or eight specimens of Gammarus. 



The breathing habits of adult Desmognathus deserve especial 

 discussion because of the lungless condition of the animal. As 

 in all amphibians the skin is a most efficient breathing organ, and 

 so long as it is kept in the normal moist condition which the 

 burrowing habit of the species insures, it probably furnishes 

 ample means for the aeration of the blood which circulates 

 through its capillary network. As is usual with amphibians 

 also, the bucco-pharyngeal cavity is made use of to supplement 

 the cutaneous respiration. Bucco-pharyngeal respiration is 

 accomplished by a rapid fluctuation of the floor of the tightly 

 closed mouth, which results in a rapid succession of movements of 

 air in and out through the wide-opened nares. Correlated 

 probably with the lungless condition, is the fact that these fluc- 

 tuations are far more rapid in Desmognathus than in the lunged 

 forms; moreover, Desmognathus in common with other lungless 

 forms (Spelerpes and Plethodon for example) possesses a relatively 

 longer oesophagus provided with muscles by means of which 

 it may be held distended, thus increasing the size of the respira- 

 tory surface by the addition of a mucous membrane which was 

 shown by the researches of H. H. Wilder ('01) and Seelye ('06) 



