296 DR. J. E. GRAY ON RHINOCLEMMYS MEX1CANA. [Apr. 4, 



Bradycinetus brenda. 

 Fig. 6. Mandibular foot of male : a, mandibular process. 



Plate XXVII. 



Philomedes folinii. 



Fig. 1. Carapace of male, outline, seen from left side. X 20. 



2. Carapace of female, seen from left side. X 40. 



3. Carapace of female, seen from above. X 40. 



4. Carapace of female, seen from front. X 40. 



5. Secondary branch of lower antenna of female. X 210. 



4. Additional Notes on Rhinoclemmys mexicana. 

 By Dr. J. E. Gray, F.R.S. &c. 



[Keceived April 3, 1871.] 



(Plate XXVIII.) 



In the 'Proceedings' of this Society for 1870, p. 659, I de- 

 scribed a species of Rhinoclemmys, under the name of R. mexicana, 

 from a specimen which we had received from M. Salle; and in 

 the month of November for the same year I figured the head of 

 the animal (P. Z. S. 1870, p. 723, fig. 4). The specimen I first 

 described appeared to have the normal colouring of the genus ; that 

 is to say, the shell appeared to be of a nearly uniform dark colour 

 above and below, with a pale margin forming a submarginal ring to 

 the sternum. The specimen since I described it has been mounted 

 and varnished ; and it now appears to be more olive- colour, slightly 

 variegated with darker streaks and imperfect irregular paler rings ; 

 and each of the dorsal shields is marked with a yellow spot, which 

 I had not observed in any other species of this natural genus. 



We have lately received from M. Boucard two other specimens 

 of Emydes from Mexico with their heads ; and, from the colouring 

 of their heads, there can be no doubt (though the shells look very 

 unlike the typical specimens of Rhinoclemmys mexicana) that they 

 belong to the same species ; and in both of them the yellow spot 

 in the centre of the areola is distinctly marked, being linear in the 

 adult and large and circular in the young. And the colouring of 

 the young explains the slightly variegated appearance of the typical 

 adult specimen first described. 



The young specimen is olive-brown above, and pale yellow-brown, 

 being darker in the central line of the sternum and over the sternal 

 costal suture, below. The marginal shields are pale-spotted, and 

 with a distinct pale semitransparent acute outer margin. The ver- 

 tebral shields have two or three ovate concentric yellow rings, most 

 distinct on the second and third, and an oblong central yellow spot, 

 which is sometimes divided in half. The costal shields have two 

 vellow subcircular rings, and a large yellow spot on the middle of 

 the large areola. The bead of this animal is coloured like that of 



