CLASS V 



CEPHALOPODA 



595 



OrthocJioanites and Gyrtochoanites. The characters of these different groups are defined 

 under their proper headings. 



Suborder A. HOLOCHOANITES Hyatt. 



Funnels of siphuncular segments reaching from the septum of origination to the plane 

 of the next septum apicad or beyond this, or in some genera even to the plane of the second 

 septum. 



I. DiPHRAGMiDA Hyatt. 



This group contains but one family, Diphragmidae^ having the same characters as 

 the following unique genus : — 



Diphragmoccras Hyatt. Orthoceracones and cyrtoceracones having simple septa 

 and sutures as in Endoceratida, but siphuncle divided by tabulae alternating with the 

 septa of the camerated shell. Chambers of siphuncle empty, as are also the camerae. 

 Quebec group. 



II. Endoceratida Hyatt. 



Orthoceracones, cyrtoceracones, gyroceracones and nautilicones having siphuncles of 

 variable diameter, but as a rule large in proportion to the width of the shell. Tlieymay be 

 empty or filled with internal organic deposits, but are invariably tubular, and the funnels 

 completely shut off the interior from the interiors of the camerae. The latter are without 

 organic deposits. 



Family 1. Endoceratidae Hyatt. 



Smooth or annulated orthoceracones. Siphuncle ahvays more or less filled with 

 organic deposits. 



A B c 



Fig. 1104. 



A, Vaginoceras duplex (Wahlenberg). Ordoviclan ; Kinnekulle, 

 Sweden. Much reduced. B, V. coi/iv/iHnc (Wahlb.). Ordovician ; 

 Oranienbaum, Russia. The anterior endocone of the siphuncle is 

 filled up with matrix so as to form a dart (" Spiess "). i/.j. C, Dia- 

 grammatic longitudinal section of the last, showing siphonal 

 funnels. D, Detached camera of V\ujinoceras with long siphonal 

 funnel. (Figs. C and D after Dewitz.) 



Fig. 1105. 



Endoceras proteiformc Hall. Ordovi- 

 cian ; New York. Longitudinal section 

 showing funnels and endocones. 



Vaginoceras Hyatt (Fig. 1104). Ordovician. Gameroceras Conrad {Sannionites 

 Fischer von Waldheim ; Suecoceras Holm). Ordovician and Silurian. 



Endoceras Hall {Golpoceras Hall; Diploceras Conrad) (Fig. 1105). Smooth or 



