294 



CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Straight width nor less than 72% ; percentage of middle height 

 exceeds percentage of front height by not less than six; curved 

 length of male more than 122% ; middle height in male not less 

 than 54% ; front height in male not exceeding 45%. James 



Island. 



T. darwini. — p. 319. 



bb^, — The sum of the curved length, front height, middle height, and 

 plastron, is less than the sum of the straight length, straight 

 width, and curved width ; or^ the front height does not exceed . 

 41% of the straight length. 



cc. — The sum of the straight width, curved width and half the 

 height to marginals is less than twice the straight length; the 

 height to marginals is not more than 7% ; the curved length 

 does not exceed 126% ; the middle height does not exceed 

 51%; the percentage of the curved width does not exceed 

 the percentage of the curved length by more than 4. 

 dd. — Pectoral plates much reduced medially, (usually) not 

 reaching the midline ; plastron longer, its percentage ex- 

 ceeding that of straight width by more than 4. Chatham 

 Island. 



T. microphyes. — p. 329, 



dd^. — Pectoral plates not more reduced than in most races, 

 meeting on the midline ; plastron shorter, its percentage 

 rarely exceeding that of straight width by more than 4. 

 Tagus Cove, Albemarle. 



T. chathamensis. — p. 323. 



cc^. — The sum of the straight width, curved width and half the 

 height to marginals is not less than twice the straight length;^ 

 or (if not) the height to marginals is more than 7% ; or the 

 curved length exceeds 126% ; or the middle height exceeds 

 51%; or the percentage of the curved width exceeds the 

 percentage of the curved length by more than four; 

 ddd. — The sum of the straight width, middle height, differ- 

 ence between front and middle heights, and width at 2nd 

 to 3rd marginals exceeds 218% ; or the difference between 

 percentages of front and middle heights not less than 26; 

 or height to marginals more than 10% ; or plastron more 

 than 87%. 



ee. — Curved length plus width at 2nd to 3rd marginals 

 minus difference between curved length and curved 

 width minus middle height equals not less than 112%. 

 Indefatigable Island. 



T. porteri. — p. 354. 



ee^. — Curved length plus width at 2nd to 3rd marginals 

 minus difference between curved length and curved 

 width minus middle height equals not more than 

 111%. Cowley Mountain, Albemarle. 

 T. sp.— p. 362. 



ddd^. — The sum of the straight width, middle height, differ- 

 ence between front and middle heights and width at 2nd 

 to 3rd marginals not exceeding 218% ; difference between 

 percentages of front and middle heights less than 26; 

 height to marginals not more than 10% ; plastron not 

 more than 87%. 



iln 2 Indefatigable and 4 dome-shaped ? ? from South Albemarle. 



SThree exceptions to this are 1 Iguana Cove, 1 Cobos, and 1 Vilamil specimen. 



