218 Dr Hrsserr on the Limestone of Burdichouse, 
M. Agassiz remarks of this family, that it only comprehends 
one genus of actual creation, the genus Cestracion ; the others 
bemg fossil; that the Hybodontes (Acass.) are equally fossil. 
Then follow the Squali, the Rays, and the Cyclostome. 
The limestone of Burdiehouse entombs thorny rays of im- 
mense magnitude, and most beautifully configurated, which it is 
impossible to contemplate without amazement. (See Plate XI, 
fig. 1, A, B, and C.) The drawings of them given in Plate XI. 
are upon a scale of one-half only of their original dimensions. 
They are treble the size of a recent dorsal ray, obligingly shewn 
me by Mr Curr of the Museum of the Royal College of Sur- 
geons, which was supposed by M. Buarnvitue to be the dorsal 
bony ray of a large Silurus of the Ganges. 
M. AGasstz confesses that he knows of no other relics found 
elsewhere to which they bear any resemblance ;—that, while the 
mountain limestone, the lias, the oolite, and the chalk formation, 
afford some very striking and decided genera, none of them re- 
semble the rays found at Burdiehouse, which he thinks ought to 
be referred to a separate genus of the family of Cestraciontes. 
He proposes to name the fish to which these rays belong the Gy- 
RACANTHUS FORMOSUS., 
It is most unfortunate that nothing is known of the Gyracan- 
thus formosus more than is indicated by these relics, which give 
the promise of a fossil monster some time or other turning up, 
equalling, if not surpassing in interest, the Megalichthys. 
The teeth, even of the Gyracanthus, are unrecognised. “It is 
not impossible,” says M. Acassiz, “ that the teeth of so remark- 
ag able an appearance, which have been discovered, may belong 
to this animal. But thisisa mere supposition, solely found- 
ed upon the analogy of what I have seen concerning the rays of 
other formations.” —I may here observe, that the teeth alluded 
to were not found at Burdiehouse, but in the important fossili- 
ferous coal-seam of Stoneyhill near Musselburgh, first brought to 
notice by the researches of Lord Grrrnock. 
