142 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Nevertheless, the examination of very large series discloses 

 certain average differences, and certain resemblances, which 

 lead us to believe that, during a considerable period of time 

 after this large island was broken up, Narborough Island re- 

 mained connected with Albemarle, as did James with Jervis, 

 and Indefatigable with the Seymours. Brattle and Cowley 

 islands doubtless were joined to Albemarle, and Bartholomew 

 to James. Curiously enough, the Tropiduri of Daphne Island 

 seem to resemble those of James Island more closely than they 

 do those of the Seymours and Indefatigable, although the lat- 

 ter lie much nearer. 



Thus we find that the evidence gathered from a study of 

 the Tropiduri points to the gradual depression and partial sub- 

 mersion of a former Galapagos Land, resulting in its division 

 into many smaller islands and islets. The story agrees in al- 

 most every detail with that which we have previously gathered 

 from an investigation of the snakes and geckos. The chief 

 points of difference are that the snake of Barrington is less 

 differentiated than the lizard, and the Tropiduri afford less 

 evidence than do the snakes of a former division into an 

 Albemarle-Narborough Island and a James-Jervis-Indefati-, 

 gable Island, 



SYSTEMATIC ACCOUNT 

 Key to the Galapagos Tropiduri 



a. — Sides of neck scaly, with fewer folds. 



b. — Scales around body not more than 65; males longitudinally 

 striped. Chatham. 



T. bivittatus. — p. 

 b.2 — Scales around body more than 65; no longitudinal stripes. 

 Bindloe. 



T. habelii. — p. 

 a. 2 — Sides of neck granular between folds; folds more numerous. 



bb. — Hind legs of males with definite blackish spots; interparietal 

 plate seldom much broader than long; scales around body 

 not more than 80. 

 c. — 36 to 48 scales in crest; smaller; Httle red in coloring. 

 Charles. 



T. grayii. — p. 

 c.2 — 50 to 61 scales in crest; larger; usually much red. Hood. 

 T. delanonis. — p. 

 bb. — Hind legs without definite blackish spots; interparietal 

 usually much broader than long; or scales around body 

 more than 80. 

 cc.^ — Scales around body more than 75. 



d. — Head above speckled with lighter spots ; no red in general 

 coloration; scales around body 85 to 101. Abingdon. 



