32 PALAEONTOLOGY OF NEW YORK. 



which attains its highest development in the Silurian. In outline and contour 

 it shows an intimate relationship with an undescribed species of Dalmanites 

 from the Lower Helderberg formation. It is, moreover, directly comparable 

 with Dalmanites spinifera, Barrande, from the etage G, and D. rhenanus, Kayser, 

 from the Wissenbach slates of the Lower Devonian. 



Distribution. Upper Helderberg group. Cayuga, Province of Ontario. 



Dalmanites (Hausmannia) Meeki. 



PLATE XI A, FIGS. 28-30. 



Dalmanites (andet. sp.), Meek. Gteol. Expl. Fortieth Parallel, vol. iv, p. 48, pi. i, tigs. 11. 11a. 1877. 



lanites Meeki, W ili ott. Monogr. U. S. Geol. Suit., vol. viii : Pal. Eureka Dist., p. 207. pi. xvii, tigs. 



5, 5a-h (not fi£. 5e). 1S84. 



The material representing this species consists of detached specimens of a 

 glabella, a very large hypostoma and a quite perfect pygidium. The last- 

 named part is very closely similar, probably identical with the pygidium of 

 Dalmanites anchiops, but if the associated glabella belongs to the same species 

 as the pygidium it will be necessary to regard these fragments as characteriz- 

 ing a distinct specific form. 



Cephalon. The glabella is very similar to that of Dalmanites pleurophjx, Conrad. 

 The frontal lobe is large and transversely sub-elliptical, depressed-convex 

 above ; the three pairs of lateral lobes are distinctly defined; the first two 

 widest at their outer extremities, the last narrow, transverse and extending 

 as an annulation across the glabella. The lateral furrows of the second pair 

 appear to he nearly obsolete toward their distal extremities, causing a tend- 

 enc3 to coalescence in the adjoining lobes. The occipital furrow is narrow 

 and shallow, the occipital ring moderately broad and elevated, and without 

 any central spine. 



Pygidium as in Dalmanites anchiops, although bearing two or three more pleural 

 annulations than is usual in mature examples of that species. 



Hypostoma elongate-triangular, surface depressed-covex. Anterior margin 

 slightly arched, antero-lateral extremities sub-auriculate. Centrum broadly 



