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 Stlurus, 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 Jchthyodorulites, 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 1 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 reqtiested and réadily received per- 
mission from its owner to draw ‘up the présent notice for the 
‘Magazine of Natural History.’ 
The specimen consists of two ‘tabulay 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. 
Tts 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 thé interior thus displaced, 
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 séen thickly beset with beautifully enamelled coni- 
