ACTINOCEKATID^. 
173 
the remaining portion having most probably been overlooked at the 
time when the other was figured. 
Barrande assigns to this species, on the autboritj^ of Comte de 
Castelnau, a specimen collected by the latter on the Little Manitoulin 
(or Cockburn) Island, Lake Huron, which differs from Stokes’s type 
in the greater distance of the septa. 
This species is distinguished from A. Bigshyi by its surface cha- 
racters and slower rate of tapering. 
Horizon. Galena Limestone, the equivalent of the upper part of 
the Trenton Formation ( = Bala Limestone Group). 
Locality. Lake Winnipeg h 
Actinoceras crebriseptum, HaU, sp. 
1847. Ormoceras crebriseptum, Hall, Pal. of New York; vol. i. p. 313, 
pi. Ixxxvi. f. 2 a, pi. Ixxxvii. ft'. 2 a-e. 
1863. Orthoceras crebriseptum, Billings, Geol. of Canada, p. 218, 
f. 228. 
1870. Orthocej'as {Onnoc.') crebriseptum, Barrande (teste Billings), 
Svst. Sil. de la Boheiue, vol. ii. Texte iii. 1874, p. 739, pi. ccccxxxiv. 
6 - 8 . 
1875. Ormoceras erebrisephim, Xicholson, Pal. of Ontario, p. 37. 
1876. Orthoceras crebriseptum, Chapman, Outline of the Geol. of 
Canada, Introduction, p. xxv, pi. iv. f. 52. 
Sp. Char. “ Elongated, conical, somewhat rapidly tapering to an 
acute apex ; septa numerous, approximate, deeply arched, distant 
about one seventh the diameter ; siphuncle eccentric, enlarging in 
each cell and contracting at its passage through the septum ; section 
circular ; surface marked by longitudinal lines, which are visible in 
the cast. This species is readily recognized by its very approximate 
septa, which are highly arched , . . {Hall.) 
Rernarlcs. The specimen representing this species in the Collection 
(which is a polished section) is remarkable for the variability of the 
diameter of the sipbuncular segments, some of the earher ones being 
larger than the later formed ones. This may possibly be due to 
curvature, by which the segments have not all been cut through 
their centres. 
^ An assemblage of fossils of Galena Limestone facies was collected by Dr. 
Hector (Q. J. G. S. vol. xvii. p. 439) on the Bed Biver, near Lake Winnipeg. 
These fossils were named by Salter, and among them was the well known 
“lead coral” of the American geologists, Beceptaculites Oweni, Hall {=E. occi- 
denialis, Salter), so characteristic of the Galena Limestone in its typical localities 
in Wisconsin and Illinois. Some of the specimens of Actinoceras Eichardsoni 
in the National Collection formed part of Dr. Hector’s collection. 
