218 



CHEL0N1A. 



setshire. The type specimen (fig. 49). The fourth to 

 the seventh neurals are shown, with the corresponding 

 costals and marginals of the left side. The 4th neural 

 articulates extensively with the 5th costal, while the 5th 



Platychelys (?) anglica. — Part of the posterior region of the carapace ; from the 

 Purbeck of Dorsetshire, f . n 4c-n 7, neurals ; c 4-c 8, costals. 



neural articulates largely with the 5th and, to a smaller 

 extent, with the 6th costal. Portions of the areas occu- 

 pied by the 3rd, 4th, and 5th vertebral shields are exhi- 

 bited. Beclcles Collection. Purchased, 1877. 



Family non det. 

 Genus ARCHiEOCHELYS, Lydekker 1 . 



Yery imperfectly known. Plastron with a series of median 

 (? azygous) shields (intergular, interpectoral, interabdominal, and 

 interfemoral) dividing the normal shields ; intergular apparently 

 placed behind the gular, as in Chelodina. Hyoplastral apparently 

 taking no part in the formation of the axillary notch, which was 

 probably constituted by the mesoplastral, as in SternotJicerus. The 

 plastron must have been of a long and narrow type. It has been 

 suggested that the carapace of this form may have had a series of 

 intervertebral shields, as in the carapace figured by Portis in the 

 * Pala)ontographica,' vol. xxv. pi. xv., and referred to Tropidemys. 



This form is only provisionally referred to the present group. 



1 Geol. Mag. dec. iii. vol. vi. p. 377 (1889). 



