PLATE XXVIII. 
Fig. a. — Augite-porphyrite. Specimen 237. Slide 237 D. Head of Minie Branch. 
In ordinary light, X 120. 
Fig. b. — Melaphyre. Specimen 87. Slide 87 D. On Gettysburg Railroad, at fourth 
cut northeast of Monterey Station. In ordinary light, X 120. 
122 
