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Figs. 4 and 5. The siphuncle is very large and propiodorsan in the 

 ephebic and gerontic stage. 



Li toe eras. 



This genus was described in Genera of Fossil Cephalopods, page 



259- 



The siphuncle is very large and is dorsad or below the centre in 

 adults, but is ventrad in Litoceras Whiteavsi in the neanic and ear- 

 lier stages, and is very likely ventrad in the young at some stage in 

 all species, as it is in those of Schroederoceras that have been 

 studied. The young are slightly costated also and the adults 

 smooth, as in other genera of similar groups. The umbilical per- 

 foration is of good size, and in the nepionic stage the shell is cyr- 

 toceran and similar to the shells of Schroederoceras of the same 

 group, but with much broader whorls and deeper umbilici. These 

 differences are maintained in the later stages of growth, the whorls 

 being much larger, broader and have in the ephebic stage similar 

 abdomens and convex, divergent sides without umbilical shoulders, 

 resembling the neanic stages of species of Schroederoceras. 



The increase by growth in the lateral diameters of the whorl is 

 rapid, as in the young of Schroederoceras and other allied genera, 

 but it continues longer, and even the adults may have very broad 

 whorls, so that these adults resemble in form the neanic stage of 

 Schroederoceras. 



The aperture is less compressed than in the full-grown shells of 

 Schroederoceras, and resemble those of the anephebic stage of that 

 genus, but are not flaring or trumpet shaped, as in Trocholites. 

 In fact, there has been a slight turning in of the edges in all the 

 specimens observed, but this, however, may be due to compression. 

 The hyponomic sinus is smaller and shallower than in the ephebic 

 aperture of Schroederoceras. 



The contact furrow is broader and deeper than in Schroed- 

 eroceras and the involution more marked on account of the rotund- 

 ity and breadth of the abdomen, which is covered in. 



The end of the whorl, even in full-grown shells, is not free, and 

 in this respect also the species resemble the neanic stage in 

 Schroederoceras. The living chambers are, so far as observed, 

 longer than in Schroederoceras and shorter than in Trocholites. 



The sutures have deep dorsal lobes, saddles on the lines of 



