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EURYSTOMITES ROTUNDUS. 



Nautilus Kelloggi, Whitf., op. cit. {Bull. Am. Mus., New York, 

 i, PL xxxi, Figs. 4, 5 ; not PL xxx). 



Loc, Fort Cassin. 



PL v, Figs. 21-25. 



This species increases more rapidly in the growth of the ventro- 

 dorsal diameters than in Kelloggi and retains the siphuncle near the 

 venter for a longer time during the growth. This may be due, 

 however, to the differences in the size, and not a matter of age, 

 since in large whorls it assumes a similar position to that of Kelloggi. 

 Fig. 21, PL v, gives a view of the first two whorls from the side, 

 partly restored from the study of the section, and the dotted lines 

 explain the position of the last section (Fig. 25, PL v) of the 

 centre of first volution. 



This figure shows the metanepionic above and paranepionic be- 

 low, just before the paranepionic comes in contact with the apex. 

 This was the last section taken. Fig. 22 shows the first section, 

 secured through the inner dorsal part of the metanepionic substage, 

 and Figs. 23, 24, PL v, show the successive sections connecting 

 this with Fig. 25, and thus demonstrating the large size of the 

 umbilical perforation and the correlative rotundity of the dorsi of 

 the meta- and paranepionic substages. 



EURYSTOMITES GIBBOSUM, n. g. 



Loc, Port au Port Choix, Schooner Island, Newfoundland. 



I mention this new species here without giving figures, because it 

 is important in the consideration of the relations of the dorsal lobe 

 and impressed zone and it is so peculiar that it can be easily recog- 

 nized. 



The general aspect is like that of Eurystomites Kelloggi, but the 

 septa are more deeply concave than in any species of these faunas 

 and the lateral sutures run forward on the sides as in Tarphyceras. 

 The outlines of the whorls in section at all epinepionic stages is like 

 that of the last whorl of the specimen of Nautilus Kelloggi, here 

 Eurystomites rotundus, as figured by Whitfield on PL xxxi, Fig. 4, 

 and in section the whorls at all stages are ovals similar to the meta- 

 nepionic substage of Eurystomites rotundus (Fig. 25, PL v), but 

 the abdomen is rounder. No lateral zones or umbilical zones are 

 differentiated, but there is a faint approximation to the digonal 

 form probably in the early neanic substages. The sides are only 



