THE VOYAGE OP THE BEAGLE 



259 



Latitude 



Summer 



Winter Mean of Summer 

 Temp. and Winter 



Tierra del Fuego. 53° 38' S. 

 Falkland Islands. 51 38 S. 

 Dublin 53 21 N. 



Temp. 

 50° 

 5i 



33°.o8 4i°-S4 



59-54 



49-37 



Hence we see that the central part of Tierra del Fuego is 

 colder in winter, and no less than aj4° less hot in summer, 

 than Dublin. According to von Buch, the mean temperature 

 of July (not the hottest month in the year) at Saltenfiord 

 in Norway, is as high as 57°.8, and this place is actually 13 0 

 nearer the pole than Port Famine ! 8 Inhospitable as this 

 climate appears to our feelings, evergreen trees flourish 

 luxuriantly under it. Humming-birds may be seen sucking 

 the flowers, and parrots feeding on the seeds of the Winter's 

 Bark, in lat. 55 0 S. I have already remarked to what a 

 degree the sea swarms with living creatures; and the shells 

 (such as the Patella;, Fissurellse, Chitons, and Barnacles), 

 according to Mr. G. B. Sowerby, are of a much larger size 

 and of a more vigorous growth, than the analogous species in 

 the northern hemisphere. A large Voluta is abundant in 

 southern Tierra del Fuego and the Falkland Islands. At 

 Bahia Blanca, in lat. 39 0 S., the most abundant shells were 

 three species of Oliva (one of large size), one or two Volu- 

 tas, and a Terebra. Now, these are amongst the best char- 

 acterized tropical forms. It is doubtful whether even one 

 small species of Oliva exists on the southern shores of 

 Europe, and there are no species of the two other genera. 

 If a geologist were to find in lat. 39 0 on the coast of Portugal 

 a bed containing numerous shells belonging to three species 

 of Oliva, to a Voluta and Terebra, he would probably assert 

 that the climate at the period of their existence must have 

 been tropical; but judging from South America, such an 

 inference might be erroneous. 



The equable, humid, and windy climate of Tierra del 

 Fuego extends, with only a small increase of heat, for many 

 degrees along the west coast of the continent. The forests 



8 With respect to Tierra del Fuego, the results are deduced from the 

 observations by Capt. King (Geographical Journal, 3830), and those taken 

 on board the Beagle. For the Falkland Islands, I am indebted to Capt. 

 Sulivan for the mean of the mean temperature (reduced from careful 

 observation at midnight, 8 a. m., noon, and 8 P. m.) of the three hottest 

 months, viz., December, January, and February. The temperature of Dublin 

 is taken from Barton. 



