1873.] 



DR. J. E. GRAY ON THE TRIONYCHID^. 



55 



6. Ida. 



Animal only known in the young state, not exhibiting the dorsal 

 bones. Sternal callosities not developed, but apparently like Lande- 

 mania. Skull short, broad ; nose very short, contracted in front, not 

 one third the length of the large orbits, which are only separated by 

 a very narrow forehead ; palate with a rather broad and deep groove 

 before the internal nostrils ; alveolar process broad. The lower jaw 

 slender, tapering, regularly rounded in front ; alveolar surface broad 

 and concave in front, with a sharp raised outer edge ; sides narrow, 

 concave on the inner side of the alveolar surface, with a raised inner 

 and outer edge. This genus is at once known from Landetnania 

 and Dogania by its shorter and more rounded nose, and by 

 the much weaker lower jaw, and especially from the latter genus 



narrowed on the front of the outer 



by the 

 edge. 



lower 



jaw 



not beinj 



Ida ornata. 

 1. Ida ornata. (Fig. 7.) 



Young only known. 



Back pale brown, with large irregularly disposed solid black spots, 

 those on the dorsal keel and on the front of the sides largest ; the 

 head darker, with white spots of irregular size and form on the 

 chin and lower side of the neck ; legs dark, with small white spots 

 on the front of the narrow edge. 



Trionyx ornatus, Gray, P. Z. S. 1861, p. 41, t. 5 (young) ; Ann. & 

 Mag. Nat. Hist. 1860, vi. p. 208, 1861, vii. p. 422. 



