184 
THE GEOLOGIST. 
dialing froai two nuclei on either side of an elevated medial line. The 
stone in which they are embedded is unquestionably the Stonesfield 
slate; it contains the characteristic Trigonia angulata, BJiynchonella, 
Ostrea, and Modiola Soicerh/ana, D'Orb. ( = pficafa, Sowerbv). The 
enigmatical bodies to which I now allude are stained of a deep red- 
ferruginous colour, the matrix retaining the grey tint and crystalline 
texture of the Stonesfield slate. On comparison between these re- 
mains and tliose of the specimens of Geomyda spinosa, from Singapore, 
in the British Museum, presented by Sir A. Smith, a comparison v.'hich 
was suggested to me by Mr. Davies, whose accurate discrimination 
first threw liglit upon the nature of the present evidence, 1 have been 
led to consider that the specimens in the Fossil Gallery represent the 
second, third, and fourth median scutes of a tortoise allied to the recent 
African species. The fossils and their corresponding impressions 
from the Stonesfield slate afford, according to my interpretation, 
evidence of the texture of the horny scutes which were developed 
outside the bony carapace of the old Oolitic tortoise. A particular 
interest is attaclied to the^e specimens, as they were considered by 
the late Edward Forbes as Trigonellites, or opercula of Ammonites. 
Since the above was written, I learn that Dr. J. E. Gray, several 
years ago, considered the present evidences to be Chelonian. I am 
indebted to my friend Mr. S. P. AVoodward, F.G.S., for this infor- 
mation, and am now aware tliat the true signification and interpreta- 
tion of these remains has been known to liim for a long period. 
COERESPONDENCE. 
RoloptycliiKS v. Glyptolepis. 
Deae Sir, — My notice of the Dura Den Glyptolepis, in 3'our number 
for March last, was merely intended to correct an impression which Mr. 
Mitchell's paper in your February number seemed calculated to convey, 
namely, that it was he who first pointed out the propriety of transferring 
Eoloptychius Flemingi from the sjenus Holoptychius to Glyptolepis. In 
doing so I seem to have expressed myself so loosely as to make it appear 
that I claimed for myself and others the merit of first noticing the crescent 
of points on the scales of that fish. This I by no means intended to do, 
as I was well aware that these had been long before observed ; indeed a 
glance at the figure given by Agassiz in his ' Vieux Gres Eouge,' pi. 22, 
fig. 1, will show that this pecuharity had not been overloolied by him. I 
was also aware that Professor Pander had expressed his belief that the 
scales of Holoptyclihis Flemingi and Glyptolepis leptopterus were the same; 
these I consider specifically distinct. But lest I might seem to claim too 
much, I forwarded to you a note to be added to my letter, which seems to 
have arrived too late for insertion, and which, by some strange mistake, 
has been printed in your number for this month (April) as the first para- 
graph of a communication from the Bev. W. S. Symonds. I may add that 
Mr. Page, of Edinburgh, was the first to point out, in my hearing, the ex- 
istence of Glyptolepis scales in the Dura Den Sandstones. 
