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also the form common in the neanic stage of species like Schroe- 

 deroceras angulatum and especially Saemanni, which it very closely 

 resembles. It is obviously an immature shell of some species of 

 this genus. 



SCHROEDEROCERAS EATONI. 



Lituites Eatoni, Whitf. (Bull. Am. Mus., New York, i, No. 8, 

 PI. xxviii (?), Fig. 5-7 et. PI. xxxii, Fig. 1 ; not Fig. 2). 



Discoceras Eatoni, Schroder (" Sil. Ceph.," Pal. Abh., Dames 

 et Kayser, v, p. 22). PI. vi, Figs. 28-35, an d PI- vii, Figs. 

 7-8- ' 

 Loc., Fort Cassin, Lake Champlain. 



Having had the original of this species, I am able to state that the 

 apex or nepionic stage is closely similar to that of Holms' figures of 

 Schroederoceras (Lit.) teres. The single specimen, Fig. 35, PL vi, 

 that showed this section has a large apical or air chamber very deep 

 and cap-shaped in outline, with abrupt ventral side, exactly as in 

 Holms' figures, the second chamber being proportionately some- 

 what less in depth. The umbilical perforation is, however, much 

 larger, as may be seen in this section, and in Fig. 31, PI. vi. 



The septa continue throughout the first and larger part of the 

 second whorl, that is during the nepionic and neanic stages, to be 

 proportionately wider apart on the venter and nearer together on 

 the dorsum until the decrease by growth in the ventro-dorsal 

 diameters in the anephebic stage makes them more equal on the 

 first quarter of the third whorl where they begin to assume the 

 usual depths. The siphuncle begins subventran in the first chamber, 

 inclining centrally in its passage through the first and succeeding 

 septa until near the end of the first whorl, when it becomes centren. 

 It is in other words nearer the venter than the centre during the 

 cyrtoceran or nepionic stage and becomes centren in the ananeanic 

 substage, as in the figure from Whitfield's specimen and in other 

 figures, PI. vi. 



The sutures have the usual broad ventral saddles and lateral lobes 

 in the nepionic stage and probably dorsal saddles, but these last 

 were not distinctly seen. 



The siphuncle in the metaneanic and paraneanic substages trends 

 slowly towards the dorsum until the third quarter of the second 

 whorl is reached, and after that the approximation proceeds more 



