312 
THE GEOLOGIST. 
" It may here be remarked that the types of igneous rock, which have 
here been deposited contemporaneously with the sedimentary strata, are 
found to be very similar to those of the intrusive rocks of other parts of 
the county, e. g. of Doonan Hill, close to the town of Donegal.- 
" On passing west from Buncrana towards Dunaff Head, through the Gap 
of Mamore, it is found that, as we approach the granite at Urrismenagh, 
the dip of the beds increases from 45° to nearly absolute verticality. The 
granite of Urrismenagh does not present many features of interest to the 
mineralogist, as the rocks in immediate contact with it are quartzose, and 
therefore unlikely to yield accidental minerals. . . . The chief point which ' 
is noticeable about the neighbourhood of Dunfanaghy is the extreme de- 
velopment of a highly cr3^stalline syenite, containing a very large propor- 
tion of titaniferous magnetic iron. The octohedral crystals of this mineral 
are very noticeable on the weathered surface of the rock." 
Hybodus and other Fossils. — Dear Mackie, — A few notes on ' Geo- 
logist,' ]Mo. 67. — P. 24d. Many specimens of shark-jaws much like, if not 
the same as, Hyhodus basanus, certainly in similar state of preservation, 
and matrix, occur in the Wealden beds near Hastings, probably in the 
middle portion of the Hastings sand series. Mr. Moore, of Hastings, and 
Mr. Beckles, have collected several specimens. The Wealden beds below 
the Perna bed (bottom of the Lower Greensand) in the Isle of Wight 
present about 100 feet of thickness above the equivalent of the Hastings 
sand ; therefore, if occurring there in the equivalent of the Hastings series, 
the Hybodus may have been found perhaps on the shore not far from the 
junction with the Lower Greensand ; nevertheless it may be truly a fossil 
from the latter. 
Page 243, etc. — "Lias Bone-bed." You might as well give the proper 
term to this at once, " Wicetic Bone-bed " (or " one of the bone-beds of the 
Upper Keuper"). The Ehretic shales at Linksfield, near Elgin, are also 
rich with Hybodus. The Linksfield shales, at first thought to be Wealden, 
were referred by Morris to the Great Oolite, but are now regarded as 
lihsetic. See my monograph on Fossil Etherise, p. 77. Sphenonchus 
Martini, Ag., also from Linksfield, is regarded by Ogilvie and Charles- 
worth as the " frontal spine " of Hybodus. 
Page 245. — In your list, after Morris, you should have kept H. stria- 
tulus to the Wealden. It would have been well if you had separated 
teeth from spines in the list. 
Page 255. — " Wiinoceros JEiruscus." 1 do not see this mentioned in 
M. Desnoyers' Memoir. 
Page 267. — Why didn't you notice the fact of Sir P. Egerton and Mrs. 
Smith's specimens of Dolichosaiirus being parts of one and the same spe- 
cimen? See Dixon, Foss. Suss. p. 388, Owen's Monog. Cret. Eept. 1851, 
p. 22, and Medals, p. 712. 
Page 268. — " Lower Greensand Reptiles." I beheve that the little cro- 
codile figured and described by Owen, Monog. 1851, p. 45, as in Saul's 
collection and from the " Lower Greensand, near Hastings," was from the 
Wealden. I saw it in Saul's collection. 
Page 270. — " Lapis frumentarius." " Lapides frumentarii" are pieces 
of Nummulitic limestone, Alreoliua limestone, and stone full of other 
Foraminifera, as the case may be, with different old authors. The sections 
of the jN^ummulites present occasionally seed-like appearances as well as 
small leaf-like objects, which latter gave rise to the terms " Saiicites," 
" Daphnis," etc. ; whilst the Alveolinae, etc., were thought to be rice 
and other grain, as millet, fescue-grass, etc. Hence the names " Phacites," 
" Seminales lapides," " Lentes lapidese," "Lapides cumini, frumentarii," 
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