24 



CATALOGUE OF SHIELD REPTILES. 



* The dorsal shields variegated or ringed ; the marginal 

 shields ivith two half rings, the centre of the ring 

 being on the suture. 



The system of colouring is most distinct in the young 

 shell ; and as the animal grows, the position of the centres 

 of the concentric rings or spots is considerably altered ; thus 

 the spot which is central in the very young animal becomes 

 more and more lateral as regards the shield it is under, as 

 the animal increases in size. To define a species properly, 

 it should be examined, compared, and described in all its 

 stages of growth, wliich has as yet been the case with very 

 few of the American Emydes. 



There are sometimes one and sometimes two centres 

 of the spots or concentric rings under each of the dorsal 

 shields ; but, in general, the centres of the spots in the mar- 

 gin are placed on or near the suture between two marginal 

 shields, so that a part of the same spots or set of rings is 

 on two neighbourmg shields. 



The colouring matter which forms the spots or varie- 

 gations on the shell, is situated in the skin under the 

 shields. The marks are much more defined and regular 

 in the young animal, and more distinct in the skin when 

 the shields are removed, than when seen through the thicker 

 shields of the older animal. The colouring matter appears 

 to be much influenced by the health of the animal ; for 

 specimens which are well marked often become less 

 marked and almost uniformly coloured in confinement, 

 rendering the distinction of specimens of shells which have 

 died in confinement very difficult ; and in many cases the 

 sternal shields themselves become thinner, and at length 

 carious, which at once shows that the shell is in a diseased 

 state, and should not be considered in its normal state of 

 colouring. 



§ The dorsal {vertebral and costal) shields with a single 

 spot or concentric series of rings on each. Sternum 

 yellow, with a large, irregular, but defined dark 

 blotch on the central line. 



12. Emys ornata. The Beautiful Emys. Tab. XII. 



Shell oblongs longitudinally rugose, olive ; vertebral 

 shields irregularly ringed ; first four-sided, second and third 

 rather long, six-sided ; costal shields with black-edged pale 

 rings round a brown spot rather below the centre ; marginal 

 shield with concentric pale rings round a posterior sutural 

 spot ; beneath yellow, with round ringed spots on the 

 suture of the marginal plates, and with a dark-edged, irre- 

 gular, greenish line down the centre of the sternum, and a 

 double one the whole length of the sterno-costal symphysis. 



Head, neck and beak with broad and naiTow vellow 

 streaks. 



Emys omata. Bell, MSS. 



Gray, Syn. 30 ; Cat. Tort. B.M. 22 ; Beechey, Foy. t. 

 Dum. ^- Bib. Erp. Gen. ii. 286 (not Synon.). 



Hub. N.W. coast of America ; New Orleans, Mexico, 

 Tampico, Yucatan. 



a. Half-grown (stuffed). Tropical America. 



j. Adult (stufl^ed). America. From the Zoological So- 

 ciety's Gardens. Tab. XII. 



I. Adult (stuffed). Costal shields longitudinally furrowed ; 

 dark-coloured rings indistinct. Mexico. 



m. Adult (stuffed). America. From the Zoological So- 

 ciety. 



k. Half-grown (stuffed). The nuchal streak on one side 

 interrupted. Mexico. 



i. Half-grown animal (dry). Plates radiately striated. 

 West Indies? Mr. Scrivener's Collection. 



A. Young (stuffed). Plates radiately striated. Mexico? 



d & e. Very young (in spirits). Areola of vertebral plates 

 with a posterior central spot and lateral streak ; costal 

 with a central spot rather below the centre, surrounded 

 with three or four regular rings ; marginal plates ^\'ith 

 a spot on hinder margin, and rings in front of it. Head 

 yellow-lined, with two broader lines on side of head. 

 Mazatlan. Presented by Alexander Collie, Esq., R.N. 



f. Very young (in spirits). Exactly like d and e. "New 



Orleans." (?) From Mus. Paris. 



" Emys concinna, Tiumeril." Mus. Paris. 



g. Very young (in spirits). Mexico, 

 c & n. Very young (dry). Mexico. 



Osteology : — 



b. Adult (shell onlv). Tropical America. Presented by 



Dr. J. E. Gray. 



13. Emys venusta. The Charming Emys. 

 Tab. XII. a. 



Shell oblong, longitudinally subrugose, olive ; vertebral 

 plates with irregular-shaped, concentric, pale rings, the 

 costal vrith more regular, concentric, pale rings round a 

 brown spot, which is rather above the centre ; marginal 

 shield with concentric rings round a posterior sutural spot. 

 Beneath yellow, with round dark s])ots on the suture of the 

 marginal spots, and darker-edged, irregular, greenish lines 

 on the central and other sutures of the plates, and a double 

 line on the sterno-costal symphysis. Head, neck and beak 

 with broad and narrow yellow streaks. 



Hub. Southern States of America ; Honduras (D?/«o«). 



