EMYS TECTA. 383 



readily distinguislied by a more depressed form, and the ab- 

 sence of the three vertebral prominences. 



Plate XXXII. represents the shell of a fossU Emys from 

 the tertiary strata of the Sewalik hills. The specimen has all 

 the mineral characters of an ancient fossil. It was embedded 

 in a hard sandstone matrix which fills the hollow of the shell, 

 and the bony part is densely infiltrated with hydrate of iron 

 and siliceons matter, so as to give it a dark colour and great 

 specific gravity. It comprises nearly the whole of the cara- 

 pace as far back as the commencement of the last vertebral 

 scute. The margin is broken off in fi'ont, and the gnlar and 

 anal portions of the plastron are also wanting. All the rest 

 of the shell is distinctly shown. It had been exposed to a 

 crash which has altered a little the form of the shell at the 

 junction of the right stemo-costai pieces with the ribs, and 

 caused a longitudinal ' fault ' on the left side of the plastron 

 between the median line and the keel. 



The fossil agrees so closely with Emys tecta in size and 

 general form that the resemblance is observed to be very 

 striking at the first glance. It has the same high-pitched, 

 roof-shaped carapace, the same tri-tubercular keel occupying 

 the first three vertebral scutes, and a similarly formed plas- 

 tron. A like agreement runs throughout the other details of 

 the characters. 



The carapace of the E. tecta is comparatively high for its 

 size, the transverse diameter being about two-thirds of the 

 length, and the height in the same proportion to the dia- 

 meter. The profile from back to front along the vertebral 

 ridge is a very depressed ellipse segment, and the horizontal 

 outline is oval with greater width at the inguinal than at the 

 humeral region. In all these particulars the fossil, in so far 

 as it has the character to show, agrees closely with the recent 

 form. It is not so high in proportion to its width as the 

 smaller sized specimens of E. tecta, but in the latter the 

 shell is observed to become more depressed with the increase 

 of size and age, the fossil being in an uitermediate condition 

 between the young and the old form. The nuchal scute in 

 Emys tecta is always small, but subject to great difference 

 in size, in different individuals. In some specimens, and 

 often the largest, it is a minute rectilineal lobule, while in 

 others it expands behind into two angular wings, the differ- 

 ence being probably sexual. It is not shown in the fossil. 

 The first vertebral scute is also subject to a considerable 

 range of difference in form. It is an irregular quadrangiilar 

 pentagon, wider in front than behind, the convergence varying 

 greatly in amoimt in different individuals. In the fossil the 

 exact form is not distinctly seen, though it seems to converge 



