FROM LYME REGIS. 243 



the greater portion of which appear to have existed during 

 the deposition of the secondary rocks of this country. In 

 1822 Mr. De la Beche figured a spine and jaw of this genus 

 in the * Transactions of the Geological Society ; ' but fossil 

 Ichthyology had at that time received little attention, and 

 even up to a much more recent period, the Ichthyodorulites 

 were erroneously imagined to belong to genera allied to Ba- 

 listes or Silurus, although a comparative examination of the 

 basal termination of these organs would have readily shown 

 the incorrectness of the supposition. Agassiz, in his general 

 observations upon the Ichthyodorulites, acknowledges the 

 valuable assistance which he received from a manuscript pa- 

 per by Dr. Buckland and Mr. De la Beche, containing the 

 descriptions of twelve species ; and he remarks that the au- 

 thors of this paper had then arrived at a knowledge of the 

 true affinities of the rays in question. 



A few weeks since Mr. Edmund Higgins, of Cheltenham,, 

 a gentleman who has for some time been a very ardent col- 

 lector of fossil remains, brought for my inspection the beau- 

 tiful specimen which forms the subject of these observations,, 

 the joint discovery of himself and Miss Anning, in the lias of 

 Lyme Regis. Appearing to be the most perfect jaw of the 

 Hybodus I had yet seen, and to possess a feature altogether 

 new to the genus, in the presence of a curved spine about 

 the region of the head, I requested and readily received per- 

 mission from its owner to draw up the present notice for the 

 ' Magazine of Natural History.' 



The specimen consists of two tabular masses, (see Sup- 

 plementary Plates, No. 4, fig. 1 & 2), on which the teeth are 

 arranged in a regular series. The larger fragment (of which, 

 in the engraving, some portion is omitted) is of a quadrate 

 shape, and from half an inch to three quarters in thickness. 

 Its anterior border is raised, slightly curved outwards, and 

 bristled with teeth, which are disposed along it in parallel 

 rows six deep, the external row being placed upon the ex- 

 treme edge. The remaining three borders have abruptly bro- 

 ken edges, and from the section of the interior thus displayed, 

 the mass, with the exception of a part of the jaw forming the 

 anterior border, appears to consist of folds of skin and por- 

 tions of bone, probably of the head, compressed together; but 

 the whole is so blended with the lias which has filled the in- 

 terstices, as to render the separation or discrimination of the 

 parts a matter of impossibility. On one surface, however, of 

 the mass, the opposite to that represented in the plate, a con- 

 siderable portion of the skin is preserved apparently uninjured, 

 and it is seen thickly beset with beautifully enamelled coni- 



