304 Dr. Du Riche Preller—Crystalline Rocks, N. Prémont. 
Portlandian. We are therefore justified in regarding the present 
specimen as a mutation from C. bononiensis to C. legayz, and we may 
refrain from giving it an independent name. 
A list of fossils from the Hartwell Clay was published on p. 227 
of the Geological Survey Memoir on the Jurassic Rocks (1895), but this 
records no echinoderm other than Pentacrinus, which name refers, no 
doubt, to columnals of Zsocrinus, since the true Pentacrinus is not 
known later than the Corallian age. f 
There are, however, other echinoderms from the Hartwell Clay, 
and if they were omitted from the list just quoted it is probably 
because Wright said that they came from the Kimmeridgian, to which 
in his time the Hartwell Clay was referred. They are the following. 
Hemipedina morrist T. Wright, Sept. 1855, Ann. Mag. Nat. Hist., 
ser. 2, vol. xvi, p. 197. Holotype, a fragment of test figured by 
Wright (April, 1858, Palaeont. Soc. Monogr. Ool. Echinoidea, p. 166, 
pl. xii, figs. 2, 6), in the Geological Dept. of the British Museum, 
reed. E 8800. The radioles referred to this species by Wright 
(1858, p. 167) are in the same Department, regd. 56879. Other 
tests are registered E 8801-8803. 
Hemipedina cunningtont T. Wright, Sept. 1855, Ann. Mag. Nat. 
Hist., ser. 2, vol. xvi, p. 198. Holotype, a fragment of test figured 
by Wright (April, 1858, Palaeont. Soc. Monogr. Ool. Echinoidea, 
p. 167, pl. xii, figs. 3 a, 5), in the Geological Dept. of the British 
*Museum, regd. 34567. 
‘“« Cidlaris spinosa, Agassiz’’: radioles provisionally referred to this 
species by T. Wright in 1857 (Palaeont. Soc. Monogr., p. 53), of 
which one was figured in 1858 (op. cit., pl. xii, fig. 6, not 4* as in 
the legend, where the reference numbers are in great confusion). 
Examples of these radioles are in the Geological Dept. of the British 
Museum, regd. 34566 & 57029; others, collected by Mr. Zedekiah 
Hunt, are in the Aylesbury Museum. The true Cidaris spinosa is 
an Oxfordian species, so it was never likely that these radioles 
belonged to it. They agree closely with the radioles of Cidaris 
legayt, and doubtless belong to the same mutation O. legayi/bonomensis 
as the interambulacrals now at last discovered by Mr. Hollis. 
IV.—Tue Crysrattine Rock-akEas oF THE PrimonTESE ALPS. 
II. Norraern Prémonr. 
By C. S. Du RIcHE PRELLER, M.A., Ph.D., M.I.H.E., ¥F.G.S., F.R.S.E. 
N the preceding paper! I described the crystalline rock-areas of the 
Maritime and Cottian Alps: I now proceed to briefly review 
those of Northern Piémont forming part of the Grajan and Pennine 
Alps, under three heads— 
I. The Lanzo Valleys and Gran Paradiso Groups. 
II. The Dora Baltea (Val d’ Aosta) Area. 
IIL. The Lanzo, Ivrea, and Val Sesia Area. 
They are shown in the sketch-map, Fig. 1. The conclusions in 
reference to the combined areas of the Piémontese Alps will be stated 
at the end of the present paper. 
1 Grou. MaG., May and June, 1916, pp. 198-205, 250-5. 
