316 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



passage throiigli the gills (those organs not having yet come into use), 

 nor otherwise than mediately through contact with the body of its 

 mother. Another adult female with young in her ovisac showed an ex- 

 cess of 9.4P in the rectum (oviduct!) and 15.6° in the heart over the tem- 

 perature of the water. In another series of fourteen observations upon 

 specimens taken with a trawl-line, and half drowned when drawn up, 

 the body temperatures had approximated that of the surrounding water. 

 In this observation, too, the Negretti-Zambra thermometer failed to act, 

 the column breaking in the wrong j^lace, so that the temperature of the 

 bottom water had to be guessed at from that of the recta of the fishes 

 and from previous observations in the same neighborhood. It was prob- 

 ably not higher than 4:2'^. Above this supposed bottom temperature 

 the fourteen half-drowned dogfish gave an excess of 2.2° in the rectum 

 and of 4.8° in the heart and "thorax." The greatest excess was 0.7°. 

 Still another series of seven taken with a line on the "Ledge," when the 

 indicated bottom temperature could not be relied on, for reasons already 

 given (see p. 313), showed an average difference between the rectum and 

 heart temperatures of 6.7°, while in another specimen the difference be- 

 tween the rectum and muscles was only l.G°. 



14. Skate {Raia eriuacea and R. Iwvis, Mitchill). Three individuals 

 of the former species, which had been half an hour with a number of 

 other fish in the trawl-net, and were therefore useless for comparison 

 with the bottom water, showed an excess in the temperature of the blood 

 over that of the rectum of 3.1°. Four individuals of the latter species 

 {R. Icevis) taken on the "Ledge," when the temperature of the water from 

 which the fish came was unknown, gave a difference between rectum and 

 circulation of 2.9°. 



SUMMARY. 



Throwing out doubtful and imperfect observations, the results of those 

 experiments in which the circumstances were most favorable to accuracy, 

 may be summed up as follows : 



Mnety-seven fishes have been observed during the summer, but many 

 of the observations are of doubtful value, as has been explained in the 

 foregoing pages. Such as the experiments are they appear to me to 

 point to the following conclusions: 



