314 PEOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



head. Could this have been the cause of the unusually high tempera- 

 ture ? The presence of spawn in the abdomen protected the rectum to 

 some extent, no doubt, from the chilling effect of the water. Another 

 specimen taken in 15 fathoms on the " Ledge" gave a difference of 3° 

 between the temperatures of the rectum and heart, the bottom tempera- 

 ture being uncertain for reasons already stated. (See page 313.) 



5. Blue-fish {Pomatomus saltatrix (Linn.), Gill). These were caught 

 on only two occasions, although often fished for unsuccessfully. Four 

 specimens on the first day and one on the second were taken by trolling, 

 and brought in after violent resistance. The average rectum tempera- 

 ture of the first four was 0.25° Jiigher, and the temperature obtained 

 by an incision into the muscles of the side 1.55° lotver than that of 

 the surface water from which the fish came (73.2°). The surface water 

 was unusually warm on this occasion, and the fishes may have come 

 from a deeper and colder stratum. Otherwise the indication would ap- 

 pear to be that they resisted in some way the higher temperature than 

 that to which they were accustomed. They were taken from different 

 schools and at different times. The single fish taken on the following 

 day showed a rectum temperature of 0.5°, and in the muscles of the side 

 1.7° above that of the surface water (70.5°). The muscles of the side of 

 this last fish, however, were only 0.5° warmer than the average (71.5°) 

 of the four taken the day before. At this time I had not yet begun to 

 observe the temperature of the blood in the heart and branchial artery. 

 Young blue-fish, 3 or 4 inches long, have been caught from the wharves 

 at difterent times, but have been too small to afford trustworthy obser- 

 vations. 



6. "Tinker mackerel" (young of Scomher scomber, Linnteus, and 

 Scomber DeJcayi, Storer). No fully-grown mackerel have been taken 

 with the line in the neighborhood of rrovincetown for several years. 

 The "tinkers," however, from G to 8 inches long, abounded toward the 

 last of the season, and upon these several observations were made at 

 different times, the temperature of the surrounding water being taken 

 at 6 feet belojy the surface, the length of line required in fishing. The 

 anus was too small to admit the bulb of my thermometers, and tempera- 

 tures were therefore taken in the stomach through the gullet, and in the 

 immediate neighborhood of the liver after dividing the larger blood- 

 vessels. The average of twelve observations gives an excess of tem- 

 perature over that of the surrounding water of 4.1° in the stomach, and 

 5.25° in the neighborhood of the liver. The individual temperatiu'es 

 were surprisingly uniform. Three specimens of young Scomber BeJcayi, 

 taken from the wharf in 8 feet of water at C0°, showed an average 

 excess of 2.3° in the neighborhood of the liver. 



7. Chogset {Tautogalabrus adspersus (Walb.), Gill). Two observa- 

 tions were made upon a single small specimen in an aquarium- tank, the 

 water being at 65.9°, and the thermometer passed iiito the stomach 

 through the gullet. The excess of temperature over that of the water 

 was 1.2°. 



