452 
tion is in contact, but this is so slight that no contact furrow is 
formed. The whorls are mostly gyroceran in the character of the 
coil becoming excentric in the ephebic stage. 
The section is a much compressed oval, the ventro dorsal diam- 
eter much longer than the transverse, the abdomen narrowly rounded 
and dorsum broader, but also gibbous. The neanic stage has a more 
rounded outline in section. 
The shell is smooth. 
The sutures have ventral and dorsal saddles with broad lateral 
lobes in the neanic and ephebic stages. 
The siphuncle varies from centroventren to intracentroventran in 
the neanic and ephebic stages. 
BARRANDEOCERAS NATATOR. 
NAUTILUS NATATOR, Bill. (Can. Wat. iv, No. 6, 1859). 
BARRANDEOCERAS NATATOR, Hyatt (Gen. Foss. Ceph., p. 299). 
Loc., Mingan Islands. 
This species has volutions compressed oval in section, the dorsum 
somewhat broader than the venter ; siphuncle is extracentroventran, 
even in the neanic stage; septa deeply concave; sutures with dor- 
sal and ventral saddles and the lateral lobes as in other species of 
this genus. 
The volutions are in contact, but no contact furrow was formed 
at any age. ‘The contact takes place as in the young of /stonio- 
ceras perforatum, Fig. 9, Pl. vii, on the venter of the paranepi- 
onic volution. 
The volution in the neanic stage, dorso-ventral diameter 13 mm., 
has a much narrower venter in proportion to the dorsum than in 
the adult. ‘The venter was rounded at all stages and also the dor- 
sum. ‘The ananeanic and nepionic stage were not present in the 
original specimen in the Museum at Ottawa, but in following out 
the same lines it is easily ascertained that the umbilical perforation 
must have been enormous, at least 15-17 mm. indiameter. The 
living chamber was somewhat over one-fourth of a volution in 
length. The whole diameter was about 108 mm. It was reported 
as having been found in the Chazy limestone. 
BARRANDEOCERAS STERNBERGI. 
NAUTILUS STERNBERGI, Barr. (Syst. Se/., Pl. xxxvi, xxxvii). 
Loc., Bohemia. PI. xiv, Figs. 2-5. 
This species has, as is usual in transitional species with gyroceran 
