TABLE OF CONTENTS. 



Chryscmys, p. 438. Clirysemys picta, p. 438. Chry- 

 semys marginata, p. 439. Chrysemys Bellii, p. 439. 

 Clirysemys oregonensis, p. 440. Chrysemys dorsalis, p. 

 440. Sub-family of Deiroehelyoida;, Deirochelys re- 

 ticulata, p. 441. Sub-family Evemydoida;, and genus 

 Emys, p. 441. Eniys Meleagris, p. 442. Sub-family 

 of Clemmydoida;, p. 442. Nanemys guttata, p. 442. 

 Calemys Miihlenbergii, p. 443. Glyptemys insculpta, 

 p. 443. Actiiiemys marmorata, p. 144. Sub-family of 



Cistudinina, p. 444. Cistudo, p. 444. Cistudo vir- 



ginea, triunguis, ornata, and major, p. 44.5. 

 Sectiox 9. The genera of Tesludinina,\>.AiG. Xerobates, 



p.446. Xerobates carolinus, 447. Xerobates Berlandicri, 



p. 447. Fossil Testudinina, p. 448. Chelonoidis, p. 



448. Megaloehelys, p. 448. Testudo proper, Chersus, 



and Psammobates, p. 449. 

 Sectiox 10. Chelonian Faunce of North America, p. 449. 



Our Turtles belong to seven different Fauna;. 



PART III. 



EMBRYOLOGY OF THE TURTLE. 



CHAPTER I . 



DEVELOPMENT OF THE EGG, FROM ITS FIRST APPEARANCE TO THE FORMATION OF THE 



EMBRYO. 



Section 1. The origin of the egg. Precautions taken 

 in the investigation. The egg originates between the 

 cells of the stroma. Initial form of the egg. Forma- 

 tion of the germinal vesicle, p. 451-457. 



Sectiox 2. Development of the yolk. Successive stages 

 in the development of the yolk ; its constitution and 

 changes at different periods. It contains at first only 

 granules, and no cells, p. 458. 



Section 3. Development of the yolk cells. Probably con- 

 nected with the first influence of copidation. Mode 

 of formation of yolk cells. Their cell wall or ecto- 

 blast, p. 463. Formation of the mcsoblast, p. 467. 

 Formation of the entoblast, p. 472. 



Section 4. The Purkinjean Vesicle. — It originates in an 

 eccentric position, p. 475. Its successive changes, p. 

 476. The Wagnerian vesicles, p. 476. 



Section 5. The growth of the ovarian egg as a whole. — 

 Dissimilarity between its two sides, one of which corre- 

 sponds to the position of the Purkinjean vesicle, and the 

 other to the opposite portion of the egg. This antago- 

 nism is carried out further during the whole life of the 

 growing animal. The ovarian egg is in fact the animal 

 itself in its first stage of development, p. 479-482. 



Section 6. The Graafian follicle and the membranes of 

 the egg. — The stroma, p. 482. The tunica granulosa, 

 p. 483. The zona pellucida, p. 484. The vitelline sac, 

 p. 485. The embryonal membrane, p. 486. 



Section 7. Fecundation. — The act of fecundation is suc- 

 cessive in Turtles. From the first copulation to the 

 time of lajing, there elapse four years, during which 

 eight copulations take place. The eggs grow for a long 

 time before tliey are fecundated, p. 489-492. 



