CORHESPONDEXCE. 
185 
Mr. Davies, in his communication in your April number, refers to the 
^eater imbrication of the scales " mentioned b)^ Mr. Mitchell " (no new- 
disco ver}), and also to the gjeneral character of the ridges on the scales, as 
being di'fierently and distinctly marked in the two genera. Undoubtedly, 
retaining the old nomenclature, the scales in H. giganteus, H. nohilissimus, 
etc., are less imbricated, and have the ridges more wary and boldh' marked 
than in H. Flemingi, but on exanuniug a large collection of the Dura Den 
fishes, a pretty regular gradation from tlie less to the more imbricated 
and from the bold wavy ridges of the larger species to the almost parallel 
and delicately marked lines found on the scales of some of the others, may 
be traced. Mr. Davies's remark as to the position of the scales showing 
tlie crescent of points scarcely corresponds w ith my experience, but this 
may very probably be occasioned by our observations being principally 
confined to different specie In H. FIcmingi many scales on every part 
of the body sufficiently preserved and exposed, which I have yet examined, 
show the crescent of pjints, while in other species these are only to be 
found on the scales along the flanks. 
I am very glad to learn from Mr. Davies that the characteristic speci- 
men of Holoptychius Andersoni in the British Museum shows, what I have 
been unable to detect in that species, the crescent of points, — as this is a 
considerable step towards clearing up the dispute Holoptychius v. Glyp- 
tolepis. Professor Huxley states in his introductory Essay to the X De- 
cade of Plates published in connection with the Geological Survey (p. U), 
" The clear recognition of the fact that this elegant structure really cha- 
racterizes Glyptolepis is of great importance, for ... it enables one to dis- 
criminate between Holoptychius {whose scales have n? semilunar area of 
hackwarclli/-directcd points) and Glyptolepis." 
I have to express ni}' gratification at the notice Mr. Davies takes of these 
communications ; to local geologists situated at a long distance from col- 
lections affording facilities for comparing the many species of such genera, 
and ever comparing nearly allied genera with one another, such hints as 
he gives are very valuable indeed. I am, dear Sir, yours truly, 
James Poweie. 
Itesicallie, April 10//;, 1863. 
Bones at Macclesfield. 
Dear Sir, — You obligingly inserted a paper from me in Vol. IV. of the 
* Geologist,' and the following communication may perhaps interest some 
of your readers : — 
A few days ago, in levelling a piece of ground as a site for an infirmary, 
a few bones and a molar tooth were discovered by the workmen. Thirty 
feet below, there is a small brook, which runs into the river, distant about 
a quarter of a mile, at a further decline of about 70 feet. The bones were 
embedded a little apart from each other, in a layer of fine sand about 18 
inches in thickness ; above that there was a deposit, about 2 yards in depth, 
of coarse sand and gravel, thickly studded with large waterworn pebbles of 
the Primary, with a few of the Secondary sandstone rocks. About 18 
inches of soil (alluvium) surmounted the whole. The excavation was con- 
tinued about 2 yards below the bed of sand in which the bones were found, 
and it consisted of thin laj-ers of gravel with marl and fine sand at irre- 
gular intervals, interspersed with carbonaceous markings and thin seams 
of drifted coal or shale. I have resided here many years, and the osseous 
remains I have sent for your inspection are the first I have seen or heard 
of; and, with the object of affording assistance to a solution of this disco- 
VOL. Ti. 2 b 
