Volume VII (_op. cit._), which from the restoration there given, made

from careful comparative measurements, would imply an individual 16 inches long.

An interesting feature of the early Devonian trilobitic faunas is the reappearance of CALYMENE in the Schoharie grit and Corniferous limestone, a fact which has been duplicated by the recent description by Dr. OEHLERT of a large species (_C. reperta_), from the lower Devonian of Saint Malo in Angers. The American Devonian species, _G. platys_, is not only the latest but the largest known representative of the genus, and for a group which at its maximum development in species and individuals in the Silurian, rarely attained considerable dimensions, the proportions reached by _G. platys_ are especially noteworthy. The entire individuals on plate 1 of Volume VII of the Palæontology show this, and the restoration accompanying a very large pygidium on plate xxv, if accurately drawn, indicates that a length of upward of eight inches was sometimes attained by the species.

No larger or more extravagantly ornamented trilobite than the _Terataspis grandis_, HALL, is known. This giant of its race has left fragments of its test in the Schoharie grit of eastern New York, and in the commingled Schoharie and Corniferous faunas of the Province of Ontario. A very complete illustration and discussion of its different parts, are given in Volume VII of the Palæontology (p. 73, pls. xvii, xviii, xix), and from these one readily obtains an idea of the structure of the cephalon, thorax and abdomen, the free cheeks alone being there unrepresented. There is, however, a very large free cheek in a fragment of Schoharie grit in the collection of the American Museum of Natural History, which in all probability belongs to this species. At the time of the preparation of this volume of the Palæontology of New York, the original specimen of Mr BILLINGS' species _Lichas superbus_, was made accessible for study by the kindness of the Director of the Geological and Natural History Survey of Canada. This specimen is a portion of the cephalon and a pygidium of _Terataspis grandis_, lying in juxtaposition on the same block, there being no doubt of their having belonged to the same animal. From this specimen it was possible to establish the relative proportions of cephalon and pygidium in this species, and from the data furnished by all the material under study, with careful comparative measurements of entire specimens of LICHAS in the collections of the State Museum, and of figures of such specimens as have been given by ANGELIN, BARRANDE and SCHMIDT, the accompanying reproduction of the original size of the animal has been drawn, its base being the largest and most complete cephalon figured in the work cited (pl. xvii, fig. 1; xviii, figs. 1, 2).

This restoration gives to the proprietor of this cephalon a length of nearly 20 inches. The figure does not however do full justice to the proportions of the animal. In the cephalon which has served as a base for the restoration the great ovoid central lobe of the glabella has a length of 2¼ inches. Mr BILLINGS speaks of a specimen of _Lichas superbus_ in which the length of this lobe was fully 3 inches. If the increase in size of this part was accompanied by the same relative increase in the size of the entire animal (and there is no good reason for assuming the contrary), such a fragment would represent an individual fully 24 inches in length, a size unsurpassed and unequaled by any other known trilobite.

With his extravagant armor of defense and aggression, _Terataspis grandis_ must have been easy lord of his invertebrate domain and no very palatable morsel for the heavily plated fishes of his day.

In the genera PHACOPS and PROETUS great size was never attained. The earlier forms of both of these genera were of inconspicuous proportions and their maximum size was attained in the middle Devonian. An entire _Phacops rana_ is figured in the Palæontology of New York, Volume VII, which has a length of 4 inches, and cephala in the Museum collection indicate an original length of 5 inches, perhaps the greatest size which has been observed in this genus. PROETUS has a still smaller habit, that is, its maximum size is never so great, and, probably, the largest example of the genus recorded is represented by a cephalon of _Proetus macrocephalus_ from the Hamilton group, which belonged to an individual fully 3¾ inches in length.

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Transcriber Note

The above article was published as part of the "Tenth Annual Report of the State Geologist For the Year 1890." (Albany, NY) on pp. 87-90 and Plate V with "Explanation of Plate V" on facing page. It was also published as part of the "Forty-fourth Annual Report of the Regents for the Year 1890" (Albany, NY) on pp. 111-114 and Plate V. Unfortunately, the available scans of these documents DO NOT include the Plate nor the Explanation pages.