134 
THE (GEOLOGIST. 
Mr. Davies to compare it with the homologous structure in the 
teeth of the Pachyrhizodus hasalis of Agassiz, which is described by 
Sir Philip Egerton, F.E.S., in Mr. F. Dixon's 'Geology of Sussex.' The 
specimen figured in that work was obtained from the Lower Chalk at 
Steyning. The characters, which are given, are — " apex very brittle, 
slightly curved inwardly, and solid ; the base is hollow, and extends 
into the substance of the jaw." It is further stated that in Sir 
Philip Egerton' s cabinet there is a specimen of this fish, exhibiting 
an unusually thick and strong humerus, as well as large and circular 
scales, covered with asperities so minute as to be indistinguishable 
without the aid of a glass. 
There are many points of distinction, however, between the FacJiy- 
rJiizo.dus hasalis of Agassiz, and Mr. Mackie's specimen. Apart from 
the absolute size of JMr. Dixon's specimen, which is at least double 
that of the one before me, I am wholly unable to detect in the 
former any trace of that curious sculptured channelling which is so 
prominent in the latter specimen. This comparison failing, Mr. Davies 
showed me some most interesting specimens, also from the Folke- 
stone gault, which exhibited equally perfect evidences of this sculp- 
turing. I would therefore suggest that some temporary or provi- 
sional name should be given to this form, which differs from the 
I'acliyrliizodus hasalis of Agassiz, both in its stratigraphical habitat 
and its odontological conformation. 
The genus Pachyrhizodus. of which comparatively so little is known, 
has been included in the family Sphyroenoida, of the great division of 
Acanthopterygian (Cycloid) fishes, in close proximity to such singular 
aberrant forms as Saurodon and Saurocephalus. AVe hope that the day 
is not far distant when some practical ichthyologist may be induced to 
examine the whole series of sauroid fishes, with a view to their ulti- 
mate division into precisely determined families. 
Pachyrhizodus gltphodus, Blake and Machie. 
Spec. Char, — Teeth with longitudinal rows of deep sculpturing, parallel with the 
dental axis. 
COREESPONDENCE. 
Glytolepis, Dura Den (Keuper Breccia). 
Deae Sie, — In claiming precedence for Mr. Pobert Walker as the first 
to make public the fact that HoloptycJiius Fleminyi belonged to the genus 
Glyptolepis, I ought to explain that this only apphes to making it known 
in this country, jprofessor Pander, in his monograph on the Saurodipte- 
riui, stated his belief that the scales supposed to belong to Platygyiathus 
Jamesoni and H. Flemingi of Agassiz, were in reality the scales of Glyp- 
tolepis leptopterics. The Professor's only mistake in this being that those 
scales belonged, not to G. leptopterus, but to a distinct species of Glypto- 
lepis, which may be called G. Flemingi. 
It may also be of interest to some of your readers to be informed that 
