BIOLOGY. 321 



ZOOLOGICAL SUMMARY. 



Vitality of tlie Salmonidce. — Mr. Miller has given the following 

 important results from his own experiments on the circulation in 

 young SalmonidcB, such as the European salmon, trout, grayling, 

 and coregonus. In the earlier state, the vitality of the Salmon- 

 idae has as its inferior limit — 2° C, and as the higher -]- -50° C. 

 With trout, and with the Salmonidaj in general, the necessities of 

 respiration increase with the temperature. Water in which the 

 fish live should be much more aerated, or more frequently re- 

 newed, when the temperature is al)ove -j- 15° C, than when it 

 remains below -|- 10° C. The transportation of embryonic eggs, 

 and of young Salmonidte, requires much less air, or less water, at 

 a low temperatui'e, than at a high temperature. The. fertilized 

 eggs will bear long journeys, and may be carried great distances, 

 if kept moist at a temperature a little above zero. The most 

 favorable temperature for the development of the young Salmon- 

 idfe is between 10° and 15° C. — Amer. Journal of Science, vol. 41, 

 18G6. 



Functions of the Air Cells in Birds. — Dr. Drosier read a paper, 

 in 1866, before the Cambridge Philosophical Society, in which he 

 maintained that tlie air-chambers in birds are not employed to 

 lessen the sjjeeific gravity of the body. The floating power of 

 the air in the sacs anil bones of the bird, when raised to the aver- 

 age temperature of the bird's body, he calculated to be in a 

 pigeon less than a grain ; therefore he maintained that the bird 

 Avas supported in the air solely by the muscular effort exerted in 

 the downward stroke of the wing. Nor are the air cells designed 

 for aerating the blood, because the vessels in them are very fine, 

 and sparsely scattered. He considered their true functions to be, 

 that, since the thoracic cells expand when the al)dominal contract, 

 and vice ^^ersa^, during the expansion and contraction of the chest, 

 a constant current of air is kept up through the lungs, and so 

 fresh air plays constantly over the capillaries in the lungs, which 

 are naked. 



Parturition in the Kangaroo. — M. Alix claims for M. Jules 

 Verreaux the discovery of the mode of pai'turition in the kanga- 

 roo. M. Verreaux kept a large number of these animals in cap- 

 tivity, and by attentive care day and night he was able to ascertain 

 the following facts. When the female feels that she is about to 

 expel an embryo, she applies her anterior jiaws to each side of 

 the vulva, so as to open its lips; then she introduces her muzzle, 

 and receives the embryo into the buccal cavity. The apertiu'e 

 of the marsupial pouch is then opened by the paws, and the em- 

 bryo drop2)ed into it from the mouth, when it soon attaches itself 

 to the mammary gland. Both Owen and Bennett had guessed 

 these facts, but M. VeiTcaux was the first to observe them. — 

 Quart. Journ. of Science, 1866. 



Incubation of Eggs in some of the Chromida;. -r- In a letter from 

 Prof. Agassiz, dated from Brazil, Sept. 22, 1865, he says : " I have 

 observed a species of Oeophagus, which I have described under 

 the name of Q. Fedroinus, the male of which carries on its Snout 



