G. C. Crick—Two Chath Cephalopods. 0450 
schists and gneisses as we find them now. This implies a similar 
history for the whole Moine system of the North of Scotland. The 
age of these rocks and the period or periods of movement that 
produced the foliation are not satisfactorily established, but that the 
movements occasioned the metamorphism is sufficiently clear. There 
may be, and probably are, in the Scottish Highlands orthogneisses 
that have a different history from the Carn Chuinneag granite gneiss. 
Mr. Barrow has shown reason to believe that near Blair Atholl some 
orthogneisses have structures developed in them by pressures acting 
during consolidation.! Similar types of gneiss are believed by Dr. Flett 
to occur in the Lizard Peninsula. But in the granite gneisses of 
Ross-shire no structures have been met with that cannot be explained 
as occasioned by the action of orogenetic pressures on normal igneous 
rocks completely crystallized. 
: | 
II.—Nore on two CrpHatopops [| P4acHYDIScUS FARMERYI, N.SP., 
AND HETEROCERAS REUSSIANUM (D’ORBIGNY) | FROM THE CHALK 
oF LINCOLNSHIRE. 
By G. C. Crick, Assoc. R.S.M., F.G.S., British Museum (Natural History) .? 
(PLATE XXVII.) 
'I\HE British Museum collection has lately been enriched by two 
Cephalopods from the Chalk of Lincolnshire that seem to be 
worthy of notice; one being a new species of Pachydiscus 
(P. farmery?), the other being referable to the genus Heteroceras. 
1. PacHypiscus FARMERYI, n.sp. (P1. XXVII, Figs. 1, 2.) 
Diagnosis—Shell (internal cast) discoidal, umbilicated; greatest 
thickness at about two-fifths of the height of the whorl from the 
suture, about three-tenths of the diameter of the shell; height of 
the outer whorl about three-eighths of the diameter of the shell. 
Whorls few, exact number unknown, probably about five; inclusion 
about one-half; umbilicus not very deep, about two-fifths of the 
diameter of the shell in width, exposing the inner whorls. Whorl 
broadly oval in transverse section, a little higher than wide; indented 
to about a quarter of its height by the preceding whorl; periphery 
broadly rounded, ill-defined ; lateral area rather inflated, not sharply 
defined from the umbilical zone; umbilical zone convex, imperfectly 
defined from the lateral area. Body-chamber occupying fully one- 
half of the outer whorl; aperture not seen. Details of chambers and 
of suture line imperfectly known. ‘The surface of the outer whorl 
with about nine curved, raised, obtusely-rounded, forwardly-projected 
ribs, each being raised on the lateral area into a transversely-elongated 
node, which, in the course of the outer whorl, passes from the vicinity 
of the umbilical margin to about the middle of the lateral area, each 
of the last four or five ribs passing into a longitudinally-flattened 
tubercle at the margin of the peripheral area; the spaces between 
these principal ribs occupied, certainly on the peripheral area and 
1 «<The Geology of the Country round Blair Atholl, Pitlochry, and Aberfeldy”’ : 
Mem. Geol. Sury., 1905, pp. 98-100. 
® Published by permission of the Trustees of the British Museum. 
