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stages of growth. The large number and great variety of form of 

 these smooth species, while still maintaining this difference of the 

 later stages of growth, shows that this separation indicates a natural 

 distinction, and I have therefore placed all under the generic name 

 of Schroederoceras, to commemorate that author's distinguished 

 services in this field of inquiry. 



DlSCOCERAS ANTIQUISSIMUM. 



Clymenia antiquissima, Eichw. (JJrwelt RussL, ii, PI. iii, Figs. 

 16, 17). 



This is a peculiar species represented in the collection in the 

 Museum of Comparative Zoology by a specimen from Porsgrund, 

 in Norway. It is heavily costated, as in the figure given by Eich- 

 wald, and these costations are deeply impressed upon the cast 

 throughout the earlier stages and in the ephebic stage. They 

 degenerate only in the gerontic stage. 



The abdomen is broader than the dorsum and the sides convex 

 and evenly rounded. The costse are very prominent and sharply 

 defined, as in the original figure. The sutures, as far as these could 

 be seen, appeared to be similar. The size was also similar and the 

 last whorl in close contact, as in Eichwald's figure of this species. 



The specimen described had reached the anagerontic stage, the 

 costae having disappeared, or, at any rate, ceased to be reflected on 

 the cast near the end of the last whorl, whereas in all previous 

 stages, except probably the earliest nepionic, they are almost 

 equally prominent on both the cast and the shell. 



The siphuncle is subdorsan at all the stages observed from what 

 appeared to be the second to the third and fourth whorls. It is 

 quite large, especially on the second whorl. 



The neanic whorl is digonal and heavily costated. The ephebic 

 and gerontic whorls are depressed ovals, the abdomens broader 

 than the dorsi. The section of the gerontic volution had ventro- 

 dorsal diameters 25 mm. and transverse 35 mm., without the shell. 

 The whole diameter of this specimen was about no mm. 



Discoceras Graftonense. 



Lituites Graftonensis, M. et W. (Proc. Acad. Philadelphia, 



1870). 

 Lituites Graftonensis, M. et W. (Geo/. III., iii, vi). 



