304 Dr. J. E. Gray on Ghelonians. 



** The second vertebral plate broader than the first vertebral plate 

 in front, trimcated at the front lateral angle, contracted behind 

 to the width of the front end of the third vertebral, with straight 

 sides. 



5. Hydromedusa flamlabris. B.M. 



The front pair of marginal plates subtriangular ; the front 

 vertebral plate twice as broad behind as long. 

 Hah. Brazil. 



This species is known from H. depressa by the smaller size 

 of the front vertebral plate and the larger size and broader 

 front lateral end of the second vertebral plate. 



It is unfortunate that we have only a single specimen of each 

 of these species ; and it is possible that what have been con- 

 sidered specific characters may be only sexual or accidental 

 difierences. 



Hydjraspis dep>ressa. 



Back broadly keeled. Costals with an obscure keel towards 

 the upper edge. The vertebral shields with an oblong spot 

 on the hinder edge of each plate ; costal shields with a minute 

 spot on the upper part of the hinder margin. The web with a 

 white spot between each of the toes, 



Hydraspis Gaudichaudii. 



Young. Head large, back of neck smooth. Pale brown, 

 minutely darker-speckled ; margin pale ; sternum and under- 

 side of margin with a large rhombic black spot covering most 

 part of the centre ; head brown, throat and lower part of sides 

 of neck, including the tympanum, white, with small brown 

 spots. 



Hah. Bahia. 



Hydraspis hicolor^ Hand-list Sh. Rept. p. 65. 



Head moderate, brown, black-varied ; face with radiating 

 short black spots and lines ; a streak from the back of the eye, 

 over the ear, along the side of the neck ; tympanum white, with 

 a black perpendicular stripe not reaching quite to the bottom ; 

 chin white, Avhich is wider on the sides, and with a black spot 

 in the middle. Shell oblong, depressed, black above and 

 below ; the lower side of the disk, the sterno-costal suture, and 

 the outer edge of the sternum white ; the sutures of the under- 

 side of the marginal plates blackish. The limbs and feet 

 blackish, with the lower sides of the thighs and hind legs grey, 

 black-dotted. 



Hah. Demerara Falls. 



