OSIKOLOGY OF THK NEW GUINEA TURTLE WAITE. 



115 



acconipanyinf-- diajirams, fi^'. 31 representing the type and fig. 32 

 the specimen now described, wliich is smaller and possibly younger 

 than the former. 



FifT. 32. 



Tlie neural plates are seven in number, but as the posterioi- one 

 is very small it may l)o that in earlier life an eighth even may be 

 developed and afterwards lost by enci-oachment of the costals. 

 The relative larger size and greater number of neurals in the 

 younger specimen suggests that a median growth of the costals 

 "takes place with age ; for they are entirely sepai-ated by the fifth, 

 sixth, and seventh neurals, and the sutures between the anterior 

 pairs of costals is not more than 3 mm., while in the type all the 

 costals meet in the mid line and the sutures referred to nearly 

 equal the length of the respective neurals. The anterior marginals, 

 of which there are ten pairs, are separated by the large nuchal, 

 and the posterior pair by the single py go-marginal . 



The absence of epidermal shields is well illustrated in the 

 accompanying photographs, where the dark lines on the inner 

 side of the carapace (PI. xxiv.) will be .seen to be coincident 

 N\-ith the sutures indicated on the dorsal surface. 



FlaHtron. — The plastron was originally described as formed of 

 nine shields, but Ramsay remarked: — "There are two small 

 portions cut away from between the second and third plates and 

 the marginals, so that it is impossible to say if these are extra 

 })lates or parts of the marginals." . . . They "are probably 

 only thecurved-in portions of the adjacent marginals." Respect- 

 ing the carapace and plastron Baur wrote : — " Both have been 

 figured by Ramsay, but tliere was some doubt about the presence 



or absence of a mesoplastral element The most 



interesting new point to be noted in the plastron is the presence 

 of a small distinct mesoplastral element. The structure of the 

 plastron is best seen from tht^ figure." 



