55 
it was resolved,—“ That the Society approves of the suggestions em- 
bodied in Mr. Wonfor’s paper, and requests the Committee to consider 
the best mode of carrying the same into effect, and to report to a 
future meeting.” 
APRIL 24TH. 
MICROSCOPICAL MEETING.—MR. T. H. HENNAH ON 
THE SCALES OF FISH. 
A system of arrangement of fishes by their scales, useful to 
geologists, but not definitive enough for existing fishes, had been 
_ devised by Agassiz, which divided scales into ganofd: enamelled 
angular thin plates, as found on the sturgeon and bony pike ; placoid: 
_ irregular points or plates of enamel, as seen in the sharks and rays ; 
_ ctenoid: horny or bony scales, with spinous or serrated margin, 
example, the perch; cyc/oid: smooth horny or bony scales, the 
3 Beaton margin being entire, as seen in the salmon, herring, &c. 
_ For a proper understanding of their place in comparative anatomy 
x it would be well to consider more generally the “ Exoskeleton of 
_ Fishes,” of which they were the most common form, so as to include 
_ those families having bony coverings. 
_ The hard shells of the Mollusca and Crustacea were external 
skeletons, requiring no internal support; between which and the 
: highly organised fish the difference of structure was apparently great, 
et, by a careful selection of examples, the transition was seen to be 
s sudden than a cursory examination would lead us to expect. 
In some of the earlier fossil fishes, such as “ Pterichthys” and 
Soccosteus,” the body was partially covered by bony plates, so dense 
1 firmly anchylosed as to constitute a dense shell, which, according 
Owen, was accompanied by an arrest of the development of the 
fernal skeleton, at an early embryonic stage. There was a recent 
example in an Indian fish, the “ Pimelodus,” which had been compared 
to ) an old dragoon in helmet and cuirass for head and ‘ial but with 
