266 THE GALAPAGOS TORTOISES. 
importations, and a multitude of tortoises already established on an island 
might not be perceptibly influenced by the advent of a few new additions from 
elsewhere. The effect of the latter would be infinitesimal, but a species re- 
duced in number of individuals, near extinction, or not yet firmly established, 
on another island might lose its identity through the advent of one or a few new 
arrivals, as may have been the case on San Salvador (James) where the species 
no longer agrees with Porter’s description, or even on Santa Cruz (Indefatigable) 
in consequence of the rumored importation by Baur, himself one of the most 
earnest advocates of the opinion that each of the islands is inhabited by a distinct 
race. The few individuals that could produce an entirely distinct race in one 
locality might be unable to produce any effect in another. In specimens of 
T. vicina recently collected there is evidence of considerable mixtures, so also 
in those of T. nigrita and of T. elephantopus. The BraGLE may or may not 
have secured one species on three islands; four species are located on Isabela 
(Albemarle). The Hassimr, 1872, obtained four species on Santa Maria that 
may be supposed with some confidence to have originated in four different 
localities, on three distinct islands. 
Comparatively little definite observation by trustworthy observers has 
been made in regard to either length of life, rapidity of growth, or rates of in- 
crease. Waite, 1899, brought together some notes of importance in the Records 
of the Australian Museum, 3, p. 95-103, pl. 20-22, in regard to a male 7. nigrita 
taken by Porter to the Marquesas, thence to Tonga, thence to Sydney and 
thence to London where it died in 1898. This follows it nearly a century, 
without determining its age in 1813. In 1896 the length of the carapace was 
4 ft. 27 inches, its width 2 ft. 11 inches and its weight 575 lbs. (p. 98). Roths- 
child gives the length of this specimen after its death as 483 inches. Waite also 
notices another of this species which weighed 56 lbs. when brought to Sydney 
in 1853. In 1893 it weighed 368 pounds. In 1896 according to Waite it was 
an egglaying female, had a length of 3 ft., a width of 2 ft. 5 inches and weighed 
3202 pounds, having lost 472 pounds in three years. Quite recently very definite 
information concerning rate of growth appeared in Science, December 31, 1915, 
p. 933, in a note by Messrs. Daggett and Heller. The specimen of 7. vicina 
had been secured, by the latter, at Iguana Cove, Isabela, June, 1899, when it 
weighed 29 pounds and was supposed to be not much over a year old; it doubled 
its weight annually. Daggett says “‘At the time of its death [April 18, 1914] 
it weighed 450 lbs. and its carcass measured 41 inches long, 31 wide and 21 
high.” In about sixteen years the individual had attained the bulk of speci- 
