ORDER CHELONIA. 1107 



Family Testudinid^:. — Following Mr Boulenger's arrangement, 

 this extensive family is taken to include the Cistudinida and most 

 of the Emydidce of other writers, and may be briefly characterised 

 as follows : The limbs terminate in free digits ; epidermal horny 

 shields are always present, but there is no intergular shield ; the 

 carapace is ovoid and fully ossified ; the plastron in the adult is 

 connected with the carapace either by suture or a straight articula- 

 tion, and is always fully ossified. There is no costiform process to 

 the nuchal bone ; the temporal fossae of the skull are not roofed 

 over by bone ; the caudal vertebrae are proccelous ; and the pubis 

 and ischium of either side unite to enclose an obturator foramen. 

 The humerus has a well-developed head, and its shaft is more or 

 less curved. The skull is of nearly equal width throughout its post- 

 orbital portion. The Terrapins and Tortoises, as the existing mem- 

 bers of this family are commonly termed, exhibit great variety of 

 habits, some being aquatic and others terrestrial ; while some, again, 

 are carnivorous and others herbivorous. Some of the terrestrial 

 forms have the normal two epidermal caudal shields of the carapace 

 fused together into a single large shield. 



We may commence our brief survey of this large family with the 

 Oriental group of Batagurs, represented by Patagur, Kachuga, Har- 

 della, and allied types. These include freshwater Terrapins, fre- 

 quently of large size, characterised by the great development of the 

 axillary and inguinal buttresses of the plastron, which divide the 

 sides of the carapace into chambers, and also by the presence of 

 one or more strong ridges on the oral surface of the palate, running 

 parallel to its alveolar borders. On the plastron (fig. 10 16) the 

 sulcus between the humeral and pectoral shields is below the ento- 

 plastral. Kachuga (including Pangshura) has the fourth vertebral 

 shield elongated, and overlying parts of four or five neural bones ; 

 the anterior neurals being elongated and hexagonal, with the short 

 side anterior. The typical K. lineata, in which the fourth vertebral 

 shield is broad anteriorly, is represented in the Pliocene Siwaliks of 

 India, which also yield the existing K. dhongoka. In a second 

 group {Pangshura), in which the fourth vertebral shield is narrowed 

 to a point at its junction with the third, we have the existing K. 

 tectum (fig. 1016) in the Pleistocene and Pliocene of India. Har- 

 della (fig. 1017) is characterised by the shortness of the fourth 

 vertebral shield, which usually extends over three neural bones 

 (four in the figure), and by the third vertebral shield overlying 

 parts of three (in place of two) neurals. It is represented in the 

 Siwaliks by the existing H. Thurgi (fig. 1017). With the exist- 

 ing American genus Chrysemys we come to forms in which the 

 axillary and inguinal buttresses are much less developed than in 

 the Batagurs, and the neural bones are shorter than in Hardella. 



