May, 1919] Silurian Fossils From Ohio 387 



were found in the Snake Hill beds in the basal Trenton, at 

 Snake Hill, New York. 



''The marginal border and interspace are as represented (in figure 

 3 on plate 9 of bulletin 162), or rather the interspace is still a little 

 wider than shown in the figure. The glabellar furrows are as faint as 

 represented, only the last lobe stands out a little more distinctly, 

 similarly as in Beecher's figures (Amer. Geol., vol. 16, 1895, p. 173, 

 pi. 9, figs. 5-7). I had still another cephalon of the Proetus from the 

 Canajoharie shale, which showed very distinctly set off basal lobes. 

 I have never seen a pygidium of Proetus undulostriatus. In the 'Cyph- 

 aspis hudsonica' (Bull. 49, 1901, pi. 4, figs. 8, 9; see also plate XIX, 

 fig 6 in the present paper) the space between the marginal border and 

 the glabella is as represented, the marginal border, however, is broken 

 at the top and the draftsman has represented its width as seen in the 

 broken part. I have no doubt that it is wider than drawn, about as 

 wide as the interspace to the glabella, as shown by the camera outline 

 (here reproduced as Fig. 6 on Plate XIX). There is no depression 

 lining the inner side of the border, nor was it intended to show one, as 

 mav be seen from the accompanying profile drawing (Fig. 9 on plate 4; 

 of Bulk 49)." 



The specimens of Proetus figured by Beecher (Loc. cit., 

 pi. 9, figs. 5-7) from the Utica shales, at Rome, New York, 

 evidently had distinctly defined basal lobes on the glabella 

 and in this respect resemble Proetus undulostriatus rather 

 than typical Proetus parviuscuhis. If the segmentation of the 

 pleural ribs on the pygidium is indicated correctly, there are 

 apparently six ribs on each side, occupying all of the space as 

 far back as the end of the axial lobe. Assuming that the ribs 

 are grooved medially, the pygidium still differs from that of 

 typical Proetus parviusculus. 



Proetus parviusculus, Hall. 

 Plate XIX, Figs. 11 A, B. 

 1872. Twenty-fourth Kept. New York State Cab. Nat. Hist., pi. 8, fig. 14. 



Proetus parviusculus is cited by Bassler, in his Bibligraphic 

 Index of American Ordovician and Silurian fossils, from the 

 Corryville member of the Maysville formation at Cincinnati, 

 Ohio (PI. XIX, Figs. 11, A, B.), and a typical specimen from 

 that horizon is figured here. 



It closely resembles Proetus undulostriatus Hall, from the glabella 

 presents essentially the same outline, narrowing toward the front, 

 with the sides slightly concave at the anterior end of the eyes. Assuming 

 that typical forms of Proetus undulostriatus are characterized by the 

 presence of more or less distinct posterior glabellar furrows, Proetus 



