Pisces. | DEVONIAN VERTEBRATA. 597 
the tail, the pedicle of which is about one-third the greatest depth of the body; caudal fin large, rhomboidal, 
obtusely pointed behind, lower side largest, the supramedial spinal prolongation extending nearly to the end; 
posterior anal fin semielliptical, equalling the depth of the body at its base in height, which is about double 
the length; both the posterior anal and dorsal fins nearly touch the caudal, and are fully their own height 
behind the anterior anal and dorsal fins, which are about one-third less in size; the pectoral fins are broad, ovate, 
scarcely two-thirds the depth of the body at their base in height, and placed nearly their own height behind 
the head. Scales about two lines high (or wide) and about one-third longer, elliptical, and with a small nearly 
central boss, round which seem to gyrate very numerous minute rough ridges, less than their own diameter 
apart, which are arranged in converging curved lines parallel with the margin of the elliptical free end of the 
scale; the small portion of the ridges anterior to the central boss are frequently broken into little tubercles ; 
the more anterior concealed portion is smooth or very minutely radiated, the (¢ articular) ridge on the under 
side strongly marked; bones of the head closely sculptured with small granules and short vermicular ridges. 
Length nearly one foot; length of exposed portion of scales slightly more than two lines. 
This beautiful fossil most resembles the Diplopteraz gracilis (M°Coy) in form, but is at once distinguished 
by the structure and sculpturing of the scales. 
Position and Locality—Rare in the Old Red sandstone of Orkney. 
Explanation of Figures.—Plate 2. C. fig. 2, natural size; fig. 2a, one scale from the back of another 
specimen, magnified three diameters. 
GYROPTYCHIUS DIPLOPTEROIDES (JM/°Coy). Pl. 2. C. fig. 3. 
Ref—M ‘Coy, Ann. Nat. Hist. 2nd Series, Vol. II. 
Desc.—Head semielliptical, depressed ; sides flattened, slightly longer than wide, pointed in front, about 
one-fifth of the entire length ; body tapering rapidly from the head to the tail, the pedicle of which is less than 
half the width of the body; caudal fin rather large, rhomboidal, nearly medial spinal prolongation slender; posterior 
dorsal fin elliptical, twice as high as long, close to the base of the caudal, and reaching about half the length of its 
lateral angle; anterior dorsal little more than half the size of the posterior ; pectorals short, broadly-rounded, 
placed rather more than their own length behind the head. Scales of the back oval, imbricated; concealed 
portion, anterior to the subcentral point, smooth or very minutely radiato-punctate, all the posterior or exposed 
portion rough, with small, irregular, minutely flexuous ridges, those of each side running parallel with the curved 
margin of the scale, and of course converging towards the middle, they are crossed by fine radiating strize ; 
scales of the sides rhomboidal, nearly square and juxtaposed, each scale articulated to the preceding and superior 
one by a narrow, smooth border on the superior and anterior sides, extending into an angular articulating 
process at the anterior superior angle (as in Osteolepis, &c.) ; the quadrate exposed portion has a small central 
point, round which the little rough ridges gyrate diagonally ; bones of the head sculptured with small vermicular 
ridges and granules. 
Length about eleven inches, greatest width of body two inches; length of exposed portion of scales about 
two lines. 
The different shape of the scales, and the wide, short, rapidly tapering figure, easily distinguish this from 
the last. 
Position and Locality —Not uncommon in the Old Red bituminous schists of Orkney. 
Explanation of Figures—P1. 2. C. fig. 3, natural size ; with a lens of low power the gyrate marking can 
be seen on the figure ; fig. 3 a, two lateral scales of do., shewing the gyrate sculpturing of surface, and the two 
articular margins, magnified three diameters. 
Genus. DENDRODUS (Oven) pars. 
Syn. ? = Asterolepis Eichw. 
Gen. Char.—Teeth large, thick, conical, straight or sigmoidally curved; surface covered with fine longi- 
tudinal ridges from the apex to the base; base dilated into an oblique, subsemicircular, rounded, flattened pad. 
