Family 3. 
MOLLUSCA 
Actinoceratidae. 
SUB-KINGDOM VI 
Orthoceracones and cyrtoceracones with siphuncle more or less filled by rings of 
organic deposits, and having an endosiphuncle in the central axis. 

Fic. 1077. 
Actinoceras cochleatum, Schloth. 
Silurian; Gottland. 
endosiphuncle. 1/y. 
Abraded fragment 
showing single septa and thick, annulated 
empty or filled to 
various degrees with 
Camerae TAY be 
organic 
deposits, even to the extent of solidifying the entire 
shell previous to gerontic stage. 
Shells smooth or 
annulated, but not longitudinally ridged, at least in 
the later stages. 
Actinoceras, Bronn. (Figs. 1077, 1078). 
ra Ye re ir 
23) WGCL 
Fic. 1078. 
Actinoceras vertebratum, Hall. 
Silurian ; Lockport, New York. 
section showing 
organic? deposits of siphuncle 
Longitudinal 
(after Barrande). 

Ortho- 
ceracones and cyrtocera- 
conesof usually depressed 
elliptical section, with 
large, excessively num- 
muloidal siphunele. 
Funnels very short and 
crumpled, sheath almost 
globular. Internal de- 
posits contracting the 
central axis into an 
annulated endosiphuncle 
with tubuli radiating 
from the annuli. Septa 
often double, with an 
interspace between the two layers near the siphuncle, but solid near the shell. 
Salle 
~ VS) ——<S=T 
KX u( < > ao 
a ; LZ 
¢ 
a Rex = uv i - 
San): 
\ 5 = Ne 


S—— 

Fic. 1079. 
Actinoceras (Ormoceras) Bayfieldi, 
Stokes. Ordovician; Lake Huron, 
Canada. Longitudinal section showing 
organic deposits of siphuncle partly 
dissolved away (after Stokes). 

Fic. 1080. 
Actinoceras (Paractinoceras) 
docens, Barr. sp. Silurian 
(2); Dvoretz, Bohemia. Ver- 
tical section showing senile 
stage without organie de- 
posits, preceded by adult 
stage with siphuneular 
rosettes (after Barrande). 
Ordovician to Carbon- 
iferous. 
Sub-genera: Ormoceras, 
Stokes (Fig. 1079). Ordo- 
vician to Carboniferous. 
Paractinoceras, sub-gen. 
nov. (Fig. 1080). Shells 
longer and more slender 

iW 
f 

Fic. 1081. 
Huronia vertebralis, 
Stokes. Ordovician; Isle 
Drummond, Lake Huron. 
Siphunele. 
than in the preceding, with large siphuncular segments confined to early stages, and 
very long living chamber. 
Cyrtactinoceras, gen. Nov. 
Type P. (Sact.) canadense, Whiteaves sp. 
Type C. (Cyrt.) rebelle, Barr. sp. 
Silurian. 
Huronia, Stokes (Fig. 1081); Discosorus, Gonioceras, Hall. 
Silurian. 
Deiroceras, Hyatt ; 
