REPORT OF THE STATE PALEONTOLOGIST I903 1 63 



crenulated to a degree shown only in pronounced development ni 

 this genus. 



The pygidium is short and stout with a short blunt axis bearing 

 four defined rings but eight axial sulci can be counted. Of the 

 pleural ribs but two can be counted and these are flat and sulcate. 



This conipletely developed Phacops is in itself indication of either 

 Devonic age or a very late stage of Siluric. In the Mississippian 

 Siluric no such form presenting fully matured cephalic features is 

 known. The species, however, shows in the sulcate pygidial ribs 

 index of early phylogenetic stage. It can not be identified with the 

 Helderbergian and Oriskany P. 1 o g a n i which is found in the 

 Perce rock and at Joli, but approaches thereto. 



2 The second species of Phacops is known only from its cephalon 

 which is of a singular and unusual type. In this the first furrows 

 of the glabella are faint without entering the dorsal furrows and are 

 like a pair of eyebrows, defining obscure round lobes, behind which 

 the second lobes are also round and better defined, while the third 

 lobes are obscure. The eyes are small and with few lenses, the 

 cheeks broad, flat and dalmanitiform, rutming out into short flat 

 spines at the angles. 



The aspect of the species is that of immaturity with reference to 

 the development of the genus Phacops and presents the combination 

 with features pertaining to Dalmanites which is indicial of the pas- 

 sage forms from the latter to the former. The aspect of this cran- 

 idium is shown in some early Devonic forms such as P. (D.) 

 t u m i 1 o b u s Clarke from the Amazonas but without association 

 with cheeks of notable Dalmanites type. 



One of these forms of Phacops indicating late age is counter- 

 balanced by the somewhat earlier expression of the other and this 

 combination is verified by the presence of Bumastus and Calymmene. 



We must call the horizon late Siluric but are disposed to make it 

 so late as to be an almost final stage in the passage from the lower 

 limestones into those of the Perce massive or lowest lower Devonic. 



The Cap Blanc limestones appear then from the evidence before 

 us to be a downthrown mass representing a part of the series shown 

 more continuously in the sea wall at Perce, and indeed such part as 



