78 



Report of the State Geologist. 



shows the acuteness of the venter and the quite direct lateral slopes of the 

 whorl to its periphery. In some specimens from the more arenaceous beds 

 the periphery appears to be erected into a knife-like edge or crest, two or three 

 millimeters in height. 



The angulation of the venter is the natural extreme of the process of 

 narrowing through which the InPwmescens whorl passes from larval stages 

 onward and which, as we have already observed, is carried further 

 forward in the var. styliopJiilwn than ever in the normal. If ever 

 approximated in the normal it could be only in non-re versional, 

 extreme gerontic stages. The great size of all such shells is, 

 of itself, corroborative evidence of such a phylogerontic con- 

 dition, as is also the rapid repetition of the septa. Again, the 

 extremely elongate-lanceolate ventro-lateral and lateral lobes, are 

 ultimates along lines already established in the growth of the 

 normal. 



No specimens thus far observed show the character of the 

 early ornamentation ; but a fragment of a large dead shell with 

 Orbiculoideas attached to the inner surface of the body chamber, 

 shows broad undulations, like pilae, concentric with the growth 

 lines (see Plate III, fig. 1). This specimen also clearly shows 

 Figure6i. Jfan- the character of the aperture of the shell. 



ticoceras oxy. Re- 

 stored outlines of The entire specimen here figured has a diameter of 200 mm.: 



final growthstage; 



jnat. size. this is from the soft shales, 150 feet below the Portage sandstone, 



at the lower Portage Falls on the Genesee river, the lowest horizon at which 

 the species has been found. A second nearly entire specimen with a diameter 

 of 320 mm. is from the Portage sandstones, in Stony Brook Glen, near 

 Dansville. Fragments of very large examples which must have measured 

 from 460 mm. to 600 mm. (18 in. to 2 feet) in diameter have been found 

 at Castile, just above the Portage sandstones, and in the flagstones below this 

 horizon in the village of Naples. 



Maxticooeras vaoans, sp. nov 



Plate VI, Figs. 11, 12. 



The high degree of acceleration indicated in Mimtic. OSOy by the sharp 

 carination of the final whorl, is carried to still earlier growth stages in a species 

 from an altogether unusual association. The fragment represented on Plate VI, 

 figures 11. 12 is all that is now known, but this is sufficiently distinctive in 



