AND DEVONIAN CONODONTS. 359 
have as yet been found in Canada; but in Russia these simple teeth 
abound in such great variety that Pander divided them into no fewer 
than seven genera, including thirty-eight species. It is also remark- 
able that neither in Canada nor in Russia do these semple teeth 
appear to extend toa higher geological horizon, though the compound 
ones in the lower rocks have a generic resemblance to those from 
the Devonian and Carboniferous. There is the still further coinci- 
dence that in Russia only traces, and in Canada none, of these bodies 
have as yet been met with in strata between the Cambro-Silurian 
and the Devonian ; but a further special search may lead to their 
discovery in the intermediate rocks. 
3. Conodonts from the Hamilton and Genesee-Shale divisions of the 
Devonian. 
In certain beds of these Devonian rocks the Conodonts appear in 
such profusion and variety of form as far to surpass those already 
described from the Siluro-Cambrian; and, judging from Pander’s 
description, they are more numerous and better-preserved than those 
in the Deyonian and Carboniferous rocks of Russia. The work of 
classifying these various forms has to some extent been simplified by 
the discovery of the specimen, already mentioned, in which a number 
of diversely shaped teeth, together with small plates, are shown to 
have appertained to the same individual, which I describe below 
under the generic name of Polygnathus. A good proportion of the 
other detached teeth in the same rocks are related to those of Poly- 
gnathus, and, for the sake of reference, will have to be described sepa- 
rately, though, judging from the remarkable combination of various 
forms in this individual, allthese teeth may have belonged to two 
or three species only. There are, however, in this type specimen of 
Polygnathus none of the more typical forms of Prionicdus with a 
very prominent elongated central or terminal main tooth, so that I 
purpose to retain this genus for similar forms. As an indication of 
the uncertainty attending the classification of these teeth from de- 
tached specimens, I may mention that in the individual example of 
Polyguathus there are teeth which Pander has placed under different 
genera. 
PrRrionropus pRRAtICUS, Hinde. (Pl. XV. fig. 14.) 
Tooth with a short, narrow, slightly arched base, at one extremity 
of which a relatively large, cylindrical, slightiy curved main tooth 
projects obliquely outwards, forming an obtuse angle with the base. 
On the base are five stout, nearly upright, smaller teeth or denticles, 
which in some specimens are more elongated than in the one figured. 
Locality and Formations. North Evans, New York State: from 
the ‘‘ Conodont-bed” of the Hamilton group. Also from Bedford, 
Ohio: in the Cleveland Shales of the Lower Carboniferous. 
PrronIopDUs ABBREVIATUS, Hinde. (Pl. XV. fig. 15.) 
Base of tooth very short and stout, at one end a comparatively 
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