EMYS MACROCEPHALA. 31 



guished from E. trijuga by having a broad triangular nuchal plate and by the lateral margins 

 of the slioll not being reverted. 



The figures (Plate II. figs. C, C) represent a specimen of the natural size. 



Emys MACROCEPHALA. The Bwad-headed Terrapen. 



Geoclemys macrocephalaj Gray, Proc. Zool. Soc. 1859, p. 478. pi. 21, and 1861, p. 139. 



Of this beautiful species I have four specimens before me : one adult, and 8^ inches long ; 

 two half-grown, of 4 inches ; and a fourth, which is only 2^ inches long, and e^ddently young. 



Form. — Shell depressed, rounded-ovate, with three longitudinal ridges, not extending on the 

 last plate of the vertebral and costal series, the ridges of the third and fourth vertebral and of 

 the second and third costal being more or less swollen behind; these prominences are very 

 distinct in young individuals. The costal ridge is twice as distant from the edge of the shell 

 as from the vertebral ridge. The upper shell is subtruncated in front, not emarginate, and 

 has scarcely any notch behind ; it is not serrated. The sternum is equally wide between the 

 axillary and inguinal incisions, its width being more than one-half of its length ; it is 

 truncated anteriorly. 



Plates. — The areolae are indistinct, situated on the posterior margins of the plates. Nuchal 

 plate subtriangular — in the young specimen nearly as broad behind as long, in older speci- 

 mens narrower. The two anterior vertebrals with the ridge much flattened ; the last vertebral 

 almost without keel, broader than the caudals. Caudals square. Gulars much broader than 

 long ; postgulars and pectorals of equal length ; the sternal portion of the abdominal square, 

 as long as prneanal ; the suture between the anals longer than their posterior margins, which 

 meet at an obtuse angle. 



Head large, broad, with the nose rather prominent and turned upwards ; jaws without 

 denticulation. Tail very short. 



Feet webbed ; forearm with very large but thin scales ; wrist wdth two or three similar 

 scales. 



Colour. — Shell chestnut-brown ; areolae black ; outer edges of the marginal plates yellow ; 

 plates on the lower side yellow, with the areolar portion black. In the young specimen the 

 sternal plates are dark purplish red, blackish on the areolae, the margins being of a mother- 

 of-pearl colour. Head black, brown above ; six yellow stripes radiate from the nose, one 

 running above the eye, the second below to the angle of the mouth ; the thii'd pair descend 

 vertically to the front incision of the upper jaw. Another yellow streak from the eye along 

 each side of the neck. The lower jaw with a pair of longitudinal streaks running to the 

 chin. 



Habitat. — Siam, Gamboja. 



