SIBERIA AND THE EXILES. 625 



and has lost it just as one species of Balanoglossus has lost it, as Mr. 

 Bateson has lately discovered. 



The littoral zone has given off colonists to the other three faunal 

 regions. The entire terrestrial fauna has sprung from colonists con- 

 tributed by the littoral zone. Every terrestrial vertebrate bears in its 

 early stages the gill-slits of its aquatic ancestor. All organs of aerial 

 respiration are mere modifications of apparatus previously connected 

 with aquatic respiration, excepting, perhaps, in the case of Tracheata, 

 trachese being most likely modifications of skin-glands, as appears prob- 

 able from their condition in Peripatus. The oldest known air-breath- 

 ing animals are insects and scorpions, which have lately been found in 

 Silurian strata. Professor Ray Lankester believes the lungs of scor- 

 pions to be homogeneous with the gill-plates of Limulus. Birds were 

 possibly originally developed in connection with the sea-shore, and 

 were fish-eaters like the tooth-bearing Hesperornis. 



The fauna of the coast has not only given rise to the terrestrial 

 and fresh-water fauna ; it has from time to time given additions to 

 the pelagic fauna in return for having thence derived its own starting- 

 points. It has also received some of these pelagic forms back again, 

 to assume a fresh littoral existence. 



The deep-sea fauna has probably been formed almost entirely from 

 the littoral, not in the remotest antiquity, but only after food derived 

 from the debris of the littoral and terrestrial faunas and floras became 

 abundant. 



It is because all terrestrial and deep-sea animal forms have passed 

 through a littoral phase of existence, and that the littoral animals re- 

 tain far better than those of any other faunal region the recapitulative 

 larval phases by means of which alone the true histories of their origins 

 can be recovered, that marine zoological laboratories on the coast have 

 made so many brilliant discoveries in zoology during late years. 



SIBERIA AND THE EXILES. 



By Dr. ALFEED E. BEEHM. 



WHOEVER associates with the name of Siberia the idea of a vast 

 prison is involved in as great an error as the person who con- 

 ceives the country as an icy desert or an interminable tundra. The 

 tundras, whose icy fields form a prominent feature in the polar regions, 

 with the stunted vegetation of their southern parts, are no myths, nor 

 is it a fiction that the Russian Government, following the example of 

 France and England, has adopted a system of penal colonies, and has 

 planted them in Siberia. But by far the larger part of this immense 

 territory has been spared the presence of convicts ; and the districts 

 VOL. xxyii. 40 



