PLETJROSTERNIDJE. 



215 



48369. Slab exhibiting the inner or tibial aspect of the left femur ; 

 from Durdlestone Bay. The middle of the shaft retains 

 its original contour, but the extremities have been crushed 

 and broken. Beckles Collection. 



48269. Several phalangeals belonging to adult individuals ; from 

 Durdlestone Bay. BecJcles Collection. 



Pleurosternum portlandicum, Lydekker, n. sp. 



Distinguished from P. bullocki by the equality in the two dia- 

 meters of the entoplastral bone, and by the narrower and pyriform 

 intergular shield. 



The type and only known specimen indicates, if adult, a compa- 

 ratively small form. Other specimens are required to illustrate the 

 full affinity of this form, which, from its much lower geological 

 horizon, may be regarded as distinct from the type species. 



Hab. Europe (England). 



Fig. 47. 



Pleurosternum portlandicum. — The plastron and adjacent marginals ; from the 

 Portland Oolite. J. ep.p, epiplastral; ent.p, entoplastral; hy.p, hyo- 

 plastral ; ms.p, mesoplastral ; hp.p, hypoplastral ; xp, xiphiplastral. 



44807. Slab exhibiting the ventral aspect of the imperfect plastron, 

 (Fig.) together with several of the marginals of the left side ; 

 from the Portland Oolite of the Isle of Portland, Dorset- 

 shire. The type specimen ; figured in the accompanying 



