PLATE VI. 
Fig. Page 
1. Pterichthys testudinarius , Ag.; dorsal (in part visceral) 
aspect of trunk and tail.—Lower Old Red Sandstone ; 
Lethen Bar. a.v.l. Anterior ventro-lateral. d. Dor¬ 
sal fin. /. Caudal ridge-scales, m.v. Median ventral. 
p.v.l. Posterior ventro-lateral. [P. 5053.] 217 
2. Pterichthys produdus , Ag. ; ventral aspect.-—Ibid. e.l. 
Extralateral (operculum). Other letters as above. 
[50111.] 218 
3. Pterichthys oblongus, Ag. ; ventral aspect.—Lower Old 
Red Sandstone; Gamrie. a.m.d. Anterior median 
dorsal, x. Caudal fin. Other letters as above. 
[P. 684 a.] 220 
4. Ditto ; ventral aspect.—Lower Old Red Sandstone; Lethen 
Bar. a. Anconeal, c. Central. 1. Lateral, m. Mar¬ 
ginal. p. Pineal (“ os dubium ”). p.m. Premedian. 
t. Terminal. Other letters as above. [50107.] 221 
5. Bothriolepis major (Ag.); cranial shield, dorsal aspect.-— 
Upper Old Red Sandstone; Alves, near Elgin, l.occ. 
Lateral occipital, m.occ. Median occipital, pt.m. 
Postmedian. Other letters as above. [38717.] 227 
6. Ditto; imperfect abraded median occipital plate, outer 
aspect.-—Upper Old Red Sandstone; Scat Craig, near 
Elgin. " [35995 a.] 227 
7. 7«, 8, 8a. Ditto: two marginal plates of appendage, the 
first edge-view and in transverse section, the second 
side-view and in transverse section.—Ibid. 
[35995 c.] 227 
9. Bothriolepis hydrophila (Ag.) ; left ventro-lateral and 
proximal portion of appendage, ventral aspect.'—Upper 
Old Red Sandstone ; Dura Den. ar. Artjcular plate 
of appendage, r. Inner transverse ridge of anterior 
ventro-lateral, exposed by removal of substance of this 
plate, ov. Overlapped inner border of the left ventro¬ 
lateral. [26121 a.] 231 
