whiteavebJ fossils OF HAMILTON FORMATION OP ONTARIO. 411 



AspiDiciiTHYS NOTABiLis (?) Whiteaves. 

 Plate 50, tigs. 1 and 2 



Cfr. Aspidichthi/s notnbili.i, Wliiteavea. 1892. This volume, pt. 4, p. 354, pi. 47, figs. 

 1 and 1 II. 



Numerous small fragments of the dermal armature of fishes, from 

 Thedford and Bartlett's Mills, with a surface ornamentation very similar 

 to that of the cranial plates of Macropetalichthys SuUivanti were identi- 

 fied with that species on page 119 of the second part of this volume. 

 Quite recently, however, the discovery, at Bartlett's Mills, of the two 

 much larger fragments represented on Plate 50, has convinced the %viiter 

 that the identification of the smaller ones with M . ^vlli'vanti is no longer 

 tenable. Both of the specimens figured are quite flat exteimilly .ind 

 hence clearly are part of the ventral region of the fish, and rot of the 

 dorsal or cranial. In both, also, there is a large, longitudinally median, 

 tuberculated aiea, and, when perfect, both evidently had a broad, smooth, 

 bevelled outer mari;in on both sides, for the overlap of lateral plates, and 

 hence must have formed part of the median element. The original of 

 fig. 1 on Plate 50 was collected in 1897 by Mr. Kernahan, who has kindly 

 presented it to the Museum of the Survey. In it n portion of the 

 smooth, bevelled surface, on each side of the tuberculated area, is pre- 

 served. The specimen represented by figure 2, on the same Plate, was col- 

 lected by Mr. Kearney, in 1875, and is also in the jNIuseum of (he Survey. 

 It is only a large portion of the right side of the plate (as viewed with the 

 ventral surface uppermost) not far from its midlength, with the margin 

 bevelled on the right of the tuberculated area, but in two directions, as if 

 for the overlap of two lateral plates. Both of these specimens are 

 evidently referable to Aspidichfliya rather than to Marropetahrlithy.f, and 

 would seem to have formed portions of the ventromedian plate of a fish 

 which at present can scarcely be satisfactorily distinguished from A. 

 notabilis. The specimen collected by Mr. Kernahan (fig. 1) probably 

 represents part of the anterior end of such a plate, though it shows no 

 indication of the transverse, terminal, crescentic bevelled area preserved 

 in the type of A. notabilis, and that collected by Mr. Kearney, (fig. 2) 

 seems to be a portion of the right side of a similar plate. 



Plate (or scale), genus and species indeterminable. 



Plate 50, fig. 3. 



The singular plate or scale represented on Plate 50, is labelled " Bosan- 

 quet, Range 3, Lot 24," and was evidently collected before the " Geology 



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