( 541 ) 
0.519 | Resp. 4, 5 and 3 freshly caught 
a Ae ) 59¢, | spec. from Utrecht, Sept. andOct., 
it, SC EDE Le: 0.526 | some of them examined in a half 
0.530 | dead condition. 
Remark. The pike in the S.E. part of the Baltic Sea leaves the coast to fairly 
great distances and is occasionally caught near Bohuslän, where 4 is at least 
0.69. Goes even some distance into the Arctic sea }). 
18 fine spec. from the Amsterdam 
Aquarium, Nov, occurs in all 
brackish bays of the Baltic Sea. 
Rudd, Leuciscus erythrophthalmus L. 0.495 
Bleak, Abramis blicca, Bloch. 0.497 12 fine spec. Aq. Amst. Nov. 
Remark. In the Baltic sea the bleak occurs in the brackisn bays. 
Trout, Salmo fario L. 0.567 1 fine spec. Ag. A/dam. Nov. 
Remark. The trout is a freshwater fish which seldom occurs in the brackish 
haffs, but belongs to the Saimonidae, a family of migratory fishes, fishes of the 
sea-coast and freshwater. Nüssrin looks upon them as original seafish. 
Waranga, Erythrinus unitaeniatus Spix. 0.577 3 fine spec. Ag. A/dam. Nov. 
Remark. Surinamian freshwater fish, living in water of 20° C. By evaporation 
during the collection of the blood the number is probably slightly too high. Also 
the quantity of blood available (8 cc.) was somewhat too small. They belong to 
the Characinidae, old genuine inhabitants of freshwater (Ostariophysi). 
Average of 13 observations on freshwater bony fishes 0°.521. 
Excluding the trout and waranga, the first as being a Salmonida, 
the other because the observation is less reliable than the others and 
because we have here a fish of which the somatic temperature is 
higher than that of the others, we obtain an average value of 0°.512, 
round which the 11 observations are pretty regularly grouped. 
To these I can add still six measurements on other cold-blooded 
freshwater vertebrates : 
Lamprey, Petromyzon fluviatilis L. 
0.473 ) Observations at Leyden, on six, resp. 
five specimens in tolerably good con- 
0.500 } dition, made in 1899. 
16 Q 
Frog, Rana esculenta L. Wire id. A fine spec, caught in the autumn. 
37 spec., Sept. 1904, animals sent from 
Berlin, kept a day ina terrarium with 
a dish of water. 
Salamandra maculosa. Laur. 9.479 
Fr.water turtle, Emys europaea. Gray. 0.474 | En heated 
Average of these: 0°.476 and of the above mentioned eleven 
together with these six: 0°.499. 
The freezing point of freshwater is about 0°.02. Borrazz’s Emys 
lived in water of this freezing point. In the tanks of the Amsterdam 
1) Paracky, Die Verbreitung d. Fische. Prag. 2e Aufl. 1895. p. 54. 
2) R. Quiyton. L'eau de la Mer, milieu organique. Paris 1904, p. 441. 
