Clarke — The Naples Fauna. 



49 



the fact that a single small concretion produced under careful manipulation, 

 500 of the young of this species alone ; together with the young of other 

 species, fully 900 specimens of immature goniatites. 



Full grown examples of Mantic. Pattersoni are not often found in associa- 

 tion with these young shells, but that the latter are of this species is clearly 

 shown by their agreement in all points with young shells obtained by the slow 

 and unhandy process of breaking back the whorls of a mature specimen. 



The Protoconch : — Shape. The embryo shell is an inflated sack with a 

 somewhat flattened or depressed distal surface. Its expansion is abrupt, so 

 that its greatest diameter is near, though not at, the distal extremity. This 

 inflation gives to the protoconch a much more considerable diameter than 

 that of the first whorl, as shown in all of our fio-ures. Viewed from its 

 extremity it has a rather narrow, transversely subelliptical outline, while from 

 the opposite side it is somewhat pear shaped, swollen above and contracting 

 below, not regularly but with a rather sudden decrease of convexity just beyond 

 the greatest expansion. 



Figures 3-10. Yiews.of the protoconch. Figs. 3, 6, Proximal or ventral aspect, passing into the nepionic 6hell; Fig. 3, 

 Similar view from opposite side. Figs. 4, 5, Protoconch and nepionic shell from the side and above. Figs. 7, 9, show the 

 distal extremity of protoconch, the latter with attached nepionic whorls. All x 25. Fig. 10, Proximal view, x 50. 



Size. In all the specimens measured, the dimensions of this elementary 

 shell are essentially the same, its width at the distal extremity being .8 mm., 

 and its length (dimension at light angles to width) being the same or .S+inm. 



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