FEEDING HABITS OF AMBLYOPSIS. 81 



RESPIRATION. 



The number of respiratory movements of Amblyopsis averaged 19 a minute in 5 

 observations, reaching a maximum of 30 in a small individual and a minimum of 

 14 in a large one. This is in strong contrast to Chologaster, the number of whose 

 respiratory motions reached an average of 80 per minute in 5 observations, with a 

 minimum of 56 and a maximum of 108 in a small specimen. Loeb has called my 

 attention to the more rapid absorption of oxygen in the light than in the dark ; this 

 extended would probably mean the more rapid absorption of oxygen through the 

 skin of light-colored animals, a matter of doubtful value, however, to species living 

 in the dark. 



The gill filaments are small as compared with the gill-cavity. In addition to 

 the oxygcnation through the gills, oxygenation probably takes place through the 

 skin. Ritter has suggested the same for Typhlogobius. 



Cutaneous respiration is not unique in Typhlogobius and the Amblyopsidas. In 

 the viviparous fishes of California the general surface, and especially the fins which 

 have become enormously enlarged, serve as respiratory organs during the middle 

 and later periods of gestation. The fins are a mass of blood-vessels with merely 

 sufficient cellular substance to knit them together. There is, however, no pink 

 coloration. 



Skin respiration would account for the extreme resistance to asphyxiation in 

 Amblyopsis and Typhlogobius. About 45 examples of Amblyopsis were carried in 

 a pail of water 400 miles by rail with only a partial change of water 3 times during 

 24 hours. A smaller number may be kept for days or weeks probably indefi- 

 nitely in a pail of water without change. The characteristics of Typhlogobius 

 along this line have been set forth elsewhere. 



FEEDING HABITS OF AMBLYOPSIS. 



The first speculations on the feeding habit of Amblyopsis are those of Cope. 

 He remarks: 



The projecting lower jaw and upward direction of the mouth render it easy for the fish to feed 

 at the surface of the water, where it must obtain much of its food. This structure also probably 

 explains the fact of its being the sole representative of the fishes in subterranean waters. No doubt 

 many other forms were carried into the caverns since the waters first found their way there, but 

 most of them were like those of our present rivers, deep-water or bottom feeders. Such fishes would 

 starve in a cave river, where much of the food is carried to them on the surface of the stream. 



The speculations of Cope are entirely erroneous as pointed out by Putnam, and 

 we shall see that the deductions based on them naturally fall to the ground. 

 Dr. Sloan recorded one Amblyopsis which he kept 20 months without food. 



Some of them would strike eagerly at any small body thrown in the water near them, rarely 

 missed it, and in a very short time ejected it from their mouths with considerable force. I tried 

 to feed them often with bits of meat and fish worms, but they retained nothing. On one occasion 

 I missed a small one and found his tail projecting from the mouth of a larger one. 



Wyman also found a small-eyed fish in the stomach of an Amblyopsis. 



Hoppin was also struck by the fact that if not capable of long fasts, Typhlich- 

 thys (Troglichthys) must live on very small organisms that the unaided eye can not 

 discern. Garman found in the stomachs of Troglichthys, collected by Hoppin in 

 Missouri, species of Ascllus, Cambarus, Ceutliophilus, and Crangonyx. 



