1897.] On the Characters of Macropetalichthys. 499 
EXPLANATION OF FIGURES. 
PLATE XII. 
Fig. 1. Fragment showing plates surrounding the left orbit, 
seen from the inside. Original in the American 
Museum of Natural History, New York (Cat. No. * ). 
Corniferous limestone, Delaware, Ohio. 
Fig. 2. Detached dorso-central plate, from Lime Rock, Genesee 
County, New York. Original in Agassiz Museum, 
Cambridge, Mass. (M. C: Z., Cat. No. 1428). 
Fig. 3. Fragment showing three detached plates of the left 
side, seen from the visceral aspect. Original in Museum 
of Oberlin College (M. No. 10). Corniferous limestone, 
Sandusky, Ohio. 
Fig. 4. Diagram showing posterior cranial angles after removal 
of the dorsal (“nuchal”) element and superjacent 
scutes. 
Fig. 5. Diagram showing arrangement of plates and course of 
sensory canals in Macropetalichthys sullivanti, X $. Vas- 
cular canals indicated by radiating lines on the right 
side only (ef. Newherry's wood-cut, Annals of Science, 
1852, No. 1, p. 12). 
Plate figures reproduced two-thirds natural size. Sensory 
canals in figs. 1 and 3 are rendered more conspicuously 
than they appear on the specimens. 
Lettering for all figures as follows: 
C, Central. P, Pineal. 
DC, Dorso-central. PeO, Preorbital. 
DL, Dorso-lateral. PtO, Postorbital. 
EO, Epiotic. ~ Sq, Squamosal. 
M, Marginal. St, Supratemporal. 
Mz, Maxillary (“malar” Cope; 
“ suborbital ” Newberry). 
