450 
lar to those of Aphetoceras, but the whorls are in contact either in 
the earlier epembryonic stages or throughout the ephebic stage. A 
departure from the spiral regularly takes place in the gerontic stage 
or earlier ; sometimes the entire ephebic stage is free. 
No impressed zone has been found at any stage, although a slight 
flattening of the dorsum was observed in one species. 
This group is represented by several species in the Newfoundland 
basin of the Quebec fauna, but it is only necessary here to describe 
one. 
DELTOCERAS PLANUM, DN. S. 
Loc., Port au Choix, on north side, Newfoundland. 
This fossil is apparently very close to Larrandeoceras natator, 
but it increases more rapidly in the dorso-ventral diameters and 
has a larger siphuncle, and this is closer to the venter and it differs 
also in the greater compression of the form. 
In the neanic stage it agrees more closely with za¢afor in aspect, 
but the siphuncle issubventran. In the ephebic stage and anage- 
rontic substage it becomes propioventran and increases in size until 
it becomes 7 mm. in diameter ventro-dorsally where it enters the 
living chamber. The transverse diameter was not measurable, but 
it is undoubtedly less than this in correlation with the compressed 
character of the volution. The ventro-dorsal diameter of the last 
whorl through the lhving chamber is 53 mm., the transverse 
only about 28 mm. to 30 mm., the whole diameter of the coil 
at this place being 163 mm. 
The incomplete living chamber is over one-quarter of a volution 
and has departed slightly from the closer spiral of the ephebic stage. 
This departure is very gradual at first until the gerontic stage begins, 
and then becomes more apparent and widens more rapidly. The 
whorls are in absolute contact only in the neanic stage. ‘The venter 
appears to be rounded at all stages of growth. 
Barrandecceras. 
This genus was described in my Genera of Fossil Cephalopods to 
include shells having large umbilical perforations, compressed 
slightly costated or smooth whorls. The venter usually narrower 
than the dorsum, the whorls barely in contact or with very slight 
contact furrow, siphuncle near but above centre, septa deeply con- 
