| 
! 
Geology. 327 
The scheme sets aside English usage altogether—which would 
write (1) Jurassic system or formation ; under this, Portlan- 
ae group or series ; and, under this, Purbeckian Sm Purbeck) 
es 
the term nian if ede abidate be given to the a prand@e subdivis-. 
Switzerland ‘and fealye and for pial second Trade 
the tell par which has the widest usage i its The 
scheme, thus m ge would be—putting in for he een grade 
re 
(1) ato 50 Gri (3) Stage ; ae ty or Substage. 
The desirableness of agreement on so mmon Sige ih 
crystalline rocks based on pe mineral constitution. Facts of 
this kind are here cited from two papers published in the Atti 
oc. Toscana di Scienza Nataral (Pisa) of Nov. 
The first, tr G. Meneghini of Pisa, ves an account 
aan Alps (ate to the northwest t of Lucea, parallel with the 
. he 
Shwe of lie. groups, ‘in tek mica ni stint, about twenty feet below 
its top occur lenticular masses of limestone (making it a calciferous 
mica schist) ; a and this limestone has afforded Meneghini a num- 
ber of Specimens of three species of Orthocerata. wo of them 
have a circular section, and a central siphuncle, and minctiess: 
Triassic Species ; but the third is elliptical m section, has an eccen- 
tric siphon, very short chambers, and is nearest to Paledeois 
kinds, swith which also the other two have near relations. At 
Mosceta, other s specimens were found in calcareous beds in the 
Upper ailete of the series, part of which may be the same with 
