CHAP, ix] ZOOPHYTES. 145 



beach (Anas antarctica), is common both here and on the west coast of 

 America, as far north as Chile. In the deep and retired channels of 

 Tierra del Fuego, the snow-white gander, invariably accompanied by 

 his darker consort, and standing close by each other on some distant 

 rocky point, is a common feature in the landscape. 



In these islands a great logger-headed duck or goose (Anas brachyp- 

 tera), which sometimes weighs twenty-two pounds, is very abundant. 

 These birds were in former days called, from their extraordinary 

 manner of paddling and splashing upon the water, race-horses ; but 

 now they are named, much more appropriately, steamers. Their wings 

 are too small and weak to allow of flight, but by their aid, partly 

 swimming and partly flapping the surface of the water, they move very 

 quickly. The manner is something like that by which the common 

 house-nduck escapes when pursued by a dog ; but I am nearly sure that 

 the steamer moves its wings alternately, instead of both together, as 

 in other birds. These clumsy, logger-headed ducks make such a noise 

 and splashing, that the effect is exceedingly curious. 



Thus we find in South America three birds which use their wings 

 for other purposes besides flight ; the penguin as fins, the steamer as 

 paddles, and the ostrich as sails : and the Apteryx of New Zealand, as 

 well as its gigantic extinct prototype the Dinornis, possess only 

 rudimentary representatives of wings. The steamer is able to dive 

 only to a very short distance It fe^ds entirely on shell-fish from the 

 kelp and tidal rocks; hence the beak and head, for the purpose ot 

 breaking them, are surprisingly heavy and strong : the head is so 

 strong that I have scarcely been able to fracture it with my geological 

 hammer ; and all our sportsmen soon discovered how tenacious these 

 birds were of life. When in the evening pluming themselves in a 

 flock, they make the same odd mixture of sounds which bull-frogs do 

 within the tropics. 



In Tierra del Fuego, as well as at the Falkland Islands, I made many 

 observations on the lower marine animals,* but they are of little 

 general interest. I will mention only one class of facts, relating to 

 certain zoophytes in the more highly organized division of that class. 

 Several genera (Flustra, Eschara, Cellaria, Crisia, and others) agree in 



** I was surprised to find, on counting the eggs of a large white Doris 

 (this sea-slug was three and a half inches long), how extraordinarily 

 numerous they were. From two to five eggs (each three-thousandths of an 

 inch in diameter) were contained in a spherical little case. These were 

 arranged two deep in transverse rows forming a ribbon. The ribbon ad- 

 hered by its edge to the rock in an oval spire. One which I found, mea- 

 sured nearly twenty inches in length and half in breadth. By counting how 

 many balls were contained in a tenth of an inch in the row, and how many 

 rows in an equal length of the ribbon, on the most moderate computation 

 there were six hundred thousand eggs. Yet this Doris was certainly not 

 very common : although I was often searching under the stones, I saw only 

 even individuals. No fallacy is wore common with naturalists, than that tin 

 numbers of an individual species depend on its powers of propagation. 



