170 AFFINITIES AND GEOGRAPHICAL 



indistinct unguiculate toes. These animals are found in tro- 

 pical regions all over the earth. Generally they are of small 

 size ; but in the Galapoagos islands Mr. Darwin found them 

 several feet in length, and we know that in the tertiary era 

 there were species in India of colossal proportions. The greater 

 number of the land tortoises are vegetable feeders, and similar 

 in disposition to the herbivorous turtles. A small group of 

 species, already adverted to, stand apart, as exhibiting imme- 

 diate affinities to the emydes. 



Seeing the various characters of the Chelonia, and keeping 

 in view the principles of the genealogical system, we have 

 good reason for believing that two or more stirpes exist in 

 this order of animals. The herbivorous species of sea and 

 land undoubtedly form portions of one family, the transition 

 from the one to the other being attended by little besides a 

 slight conversion of the extremities, a maturing of the develop- 

 ment of the osseous case, and that reduction of bulk which is 

 everywhere seen in terrestrial advances from marine originals. 

 Another stirps, perhaps starting in the coriaceous turtle, in- 

 volves the Tryonices, or Soft Tortoises, which may be regarded 

 as having merely passed from a marine to a fluviatile life, as 

 has been done in many other instances. The Emydes, for 

 which an original may be found in some of the other carni- 

 vorous turtles, constitute another line terminating in certain 

 land species. On the chelydes it would perhaps be premature 

 to speculate. In our investigations in this order, it is highly 

 instructive to mark the improvement in the filling up of the 

 interstices of the osseous frame as we advance from the marine 

 and fluviatile species. These interstices are seen in the youth 

 of the emydes and land tortoises, but as age advances they are 

 obliterated. But what is in them a youthful and transient 

 character, is permanent in the former animals, marking clearly 

 their precedence in the genealogical scale. 



No better word than SAURIA seems attainable for the 

 greatly varied order which next occurs, a combination of all 

 the loricate and squamate reptiles. The crocodile, the lizard, 

 and serpent, will suggest the principal forms to those least 

 acquainted with zoology. They are extensively distributed 



