282 THE GALAPAGOS TORTOISES. 



Specimens of from thirty-one to thirty-eight inches, Plates 14, 16, show 

 the edges of the shells to be more modified and the backs to be more depressed, 

 especially in the male, in which they have become subquadrate. The sternum 

 is nearly truncate, is deeply concave and the slight constriction at the fourth 

 and the eighth pairs of marginals is evident in both sexes. None of the speci- 

 mens show decided bosses on the areolar spaces of the dorsal scutes. 



The specimen, Plate 12, was received in exchange from Van Denburgh, 

 from Villamiel, southeastern Isabela (Albemarle); its affinities are evident 

 on comparisons with his Plates 66, 68, 83, 84, 90, 92, and others. Plates 14, 

 16 of the present work are photographed from large specimens brought by Baur 

 from the same locality. Plate 15 shows outlines of T. elephantopus Giinther, 

 1875 and 1877 (not of Harlan, 1827), from drawings by Ford of a specimen the 

 history of which was unknown. Much dependence was placed on the skull of 

 the same specimen for distinction from other species. The differences appear 

 to be individual rather than specific. The occipital crest affords the greatest 

 variance; that crest, however, figured in Giinther's, 1875, Plate 38, fig. A, and 

 1877, Plate 43, fig. A, had been broken or mutilated and in its repair took on a 

 peculiar shape not occurring on other specimens. Young to medium sized 

 specimens favor T. microphyes Giinther, 1875; the old ones agree better with 

 T. elephantopus Giinther, 1875, = T. guntheri Baur, 1889. 



On Plates 17 and 18 are figures of No. 4479 M. C. Z. and on Plate 19 is a 

 photograph of No. 4476. These are the smallest specimens of this species in 

 the collection; they were purchased by Prof. Louis Agassiz on Santa Maria. 

 A description of No. 4476 will answer about as well for No. 4479, they are so 

 nearly of the same size and appearance. No. 4476 has a rather plump appear- 

 ance, being well and smoothly rounded on the sides and back. The indentation 

 or concavity on the first to the third marginals is shallow and these scutes are 

 but little turned upward. The indentation of the eighth marginal is not very 

 distinct. The bosses on the vertebrals are low, the most marked being that 

 on the first of the series; there are no bosses on the second and third, and none 

 on the costals. Instead of a sharp ridge along the flank as on T. vicina this 

 portion is rounded and smooth, the carina making its appearance far in front, 

 in the fourth marginal, and far back, in the seventh. The declivity in the first 

 vertebral scute, the descent to the neck, is a little steeper than on older speci- 

 mens; the greatest height is attained in the third vertebral. There is a large 

 area in the central portion of each scale on which the striae are effaced, either 

 by sloughing or by scouring; nearer the edge there are seven or eight more 



