NOTES. ' 431 



December, and then exposed to freezing for li days, at 6' C, yielded a 

 large number of larvEe. The fully developed Zepidurus product-us can 

 bear a temperature only of from 0° to 18°C. 



The eggs of a species of Apiis from Khartoum, on the other hand, 

 developed in great numbers at 25°C. 



Compare on this subject the data given in ' Saison-SivwrjjMsmus ' by 

 "Weissmann, as to the accelerated development of different individuals 

 of the same species of caterpillar under a raised temperature. 



Note 49, page 132. Mobius says : ' Mollusca, Crustacea, and worms 

 which occur in the deepest parts of the Arctic Ocean, are also found in 

 the shallow portions of the Baltic ; but they are much larger than those 

 in our milder latitudes, because no extreme changes of temperature there 

 interrupt the quiet order of the vital processes, as they do in our more 

 variable seas.' 



jVbte 50, page 133. Mr. Buxton himself has not given any account 

 of the matter. I have taken my information from an interesting paper 

 by Herr B. Friedel, in the Zoohgiselien QaHen, 1871, p. 65. In the 

 winter of 1867-68, the cold in Mr. Buxton's wood marked —7° C, and 

 yet not one cockatoo perished. Strangely enough, the Carolina parrot 

 {Psittacus caroliiienns) suffered most, though in America it is distributed 

 as far as Canada ; while the true tropical Cockatoos of the Moluccas 

 throve extremely well. It is to be regretted that this experiment of 

 Mr. Buxton, who is now dead, should not have been still further carried 

 out by his brother. 



A'ote 51, page 136. Mobius says : ' We ought not to be surprised a( 

 finding eggs of mollusca and of worms in the depths of the Gulf of Kiel 

 at every season of the year, even when it is covered with ice. On 

 January 26, 1 862, a stake was pulled out of ice which had been formed 

 eight days, to which clung clusters of the eggs of Dendronottos arim-escens 

 and JEoUdw. Nevertheless, most of our Opisthobranchiata spawn most 

 freely from May to July.' Hence a certain periodicity is displayed in 

 the Gulf of Kiel ; and it would seem, according to Mobius, that the young 

 brood is caught in the greatest abundance soon after the time lyhen the 

 deposition of eggs has reached its greatest height, while large specimens 

 are found all the year round. 



Nate 52, page 136. In the Gulf of Kiel the mean monthly tempera- 

 ture varies, at the depth of 16 fathoms, between a maximum of 14° and 

 a minimum of IS" C. In the Philippines the difference between the 

 extreme monthly mean of the temperature of the air reaches at the 

 utmost 7°. In the Baltic and in England, as remarked by Meyer and 

 Mobius, at the same depth, the water is much less strongly afiEected by 

 variations in the temperature of the air. To what depth these variations 

 do in general affect our seas is not known, and it must at any rate be 

 greatly influenced by local conditions. 



Note 53, pa,ge 136. The largest number of Aspidochireice in the 



