I Have not hitherto seen any specimen so Satisfactorily and finely illustrative of the affinity of Strophodus to Cestracion as that figured in Plate VII. and which is now in the British Museum. It consists of the major part of the dental covering of a jaw, including the posterior part of the symphysis, and shows that the principal or largest, as in Cestracion. These are followed by two rows (at least) of smaller crushing teeth, and are preceded by rows of teeth both smaller and more produced at the middle of their working surface, and in the same degree changing from the crushing molar to the conical prehensile type. This dental coating or armature is imbedded in a block of the fine Oolitic building-stone from Caen, which has taken the place of the dissolved cartilaginous support of the teeth, so as to maintain and exhibit the curve of the arch (fig.1a) by which the teeth obliquely overspanned the jaw to which they were originaly attached.