Clarke — The Naples Fauna. 



47 



diminished. The great lateral saddle, by this process, becomes often much 

 broadened but less convex, while the lateral and ventro-lateral lobes, the former 

 acute and the latter linguate or sagittate, are likewise broadened and blunted. 

 It is often the case that the ventral lobes are unduly shoved to one side and made 

 to appear as though belonging to the lateral course of the suture. On Plate 

 III, fig. 4, is given an illustration of such a form from the flagstones which, 

 shows to what an extreme the modification from maceration or abrasion of 

 one-half of the shell, may be carried. The lateral lobe is almost obliterated, 

 the ventro-lateral lobe extremely abbreviated, the great lateral saddle notably 

 magnified in width and the ventral lobe turned into the apparent lateral 

 course of the suture. The outline of the septa here is almost a median 

 section of the septum in the Pattersoni-tjj)e. It is to be added that the thick- 

 ness of the fossil is but a small fraction of an inch. Its aspect is that of a nautiline 

 goniatite similar to the Gon. Tloemeri, Holzapfel.* 



Manticoceras Pattersoni extends upward in the rock series above the 

 original limit of the Portage group. It is present in the Wiscoy beds, lying 

 above the Portage sandstones and further upward the species is, in rare 

 instances, associated with the rich brachiopod fauna of the Chemung formation- 

 A few specimens collected in the beds of the middle part of the Chemung 

 group, from the quarries at Elmira, Chemung county, are the only ones which 

 have come under my observation, and these show no feature which will justify 

 a separation from the Patterson! type. All are large and some show a gerontic 

 condition in the close crowding of the septa of the final volution. 



Abnormals. Another expression of the species is a form which we 

 have designated by the varietal term styliophihim, inasmuch as it is the 

 form assumed by Momt. intumescens with its earliest appearance in the 

 Styliola limestone. This variation is of persistently smaller size than the 

 normal, seldom exceeding at maturity a diameter of about 

 fifty mm., but at this size it has the section of the body 

 volution in an even more progressed condition than that of the 

 adult Pattersoni; that is, while the inner or dorsal slope is 

 abrupt, the broad lateral slopes are at first, near the inner curve, 

 convex and thence ventrally become gently concave, while 

 the venter is bluntly rounded and the slight concavity of 

 the sides gives it a certain degree of prominence. Brief Ki ^ rp 2 . m^hco 

 consideration of the figures here given here will be sufficient to ^pm« m. aTction"i 



, i , ,1 « i -in f^iil Ana' whorl, somewhat 



demonstrate that this narrow and compressed form ot the whorl enlarged. 



* Palaeontographica, XXVIII, III, N. F. iv, pi. 2. (42), fig 1, from the Intumescens-zone of Westphalia. 



