Since the publication of Agassiz' ‘Poissons Fossiles’ only one addition, that we are aware of, has been made to our knowledge of this interesting genus of fishes,—certainly, at least, in respect to British geology. In 1845 Sir Philip Egerton described, before the Geological Society, a large jaw, or rather mouth of teeth, of a fish of this kind, found by Captain Ibbetson in the Isle of Wight, and named by Sir Philip Hylodus bassanus.

This species has been assigned to the Lower Greensand, in Morris's Catalogue, but the bed seems, from Sir Philip's statement, to be in a dubious position, for he speaks of it only as “near the junction of the Lower Greensand and Wealden,” and says the specimen was sent to him “in the hopes it might tend to show to which of the two formations its bed should be assigned,”—a question he further declines to answer, as “the evidence it affords on this question is neither direct nor conclusive, inasmuch as it is an undescribed species; and consequently any deductions beyond those based upon general affinities would be unwarrantable.” Sir Philip adds, however, further on: “The geological inferences afforded by the specimen are briefly told. The species is new. The genus is undoubtedly Hybodus. This genus attains its maximum expansion in the Oolitic series, but it ranges from the Muschelkalk to the Chalk inclusive.