628 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 22, 
Kupferschiefer of Richelsdorf and the Eisleben district, where it 
appears to be-very rare. 
Dorypterus is pretty regularly oval in contour, inclining to oyate, 
the posterior slopes being more rapid than the anterior, and the 
head rather obtuse. It was probably much compressed, and. is very 
deep in proportion to its length ; the length of the body, including 
the central rays of the tail, is about twice its depth at the 
deepest part. Our largest specimen is 5 inches long, including the 
tail, and 27 inches deep; and the head, from the anterior extremity 
of the mandible to the posterior angle of the gill-plate, is about one- 
third the length of the entire animal, including the centre rays of 
the tail. The muzzle is obtuse, the mouth shutting upwards; the 
mandibles are long, flat, and rather wide; the preemaxille are about 
half the length of the mandibles, and, like them, are flattened and 
wide ; the maxille are about as long as the premaxille, and bend 
downwards, and overlap the posterior portions of the mandibles. 
The gape was large; and the jaws probably shot out a little when in 
action ; no teeth have been observed. 
The orbits (Pl. XLII. fig. 1, wv) are large, and are situated imme- 
diately behind the premaxille and a little below the brow or dorsal 
ridge; the gill-plate or operculum (s) seems to be composed of two 
pieces, and is of a narrow crescent-ftorm, the posterior margin being 
a little angulated, the angle projecting above the middle longitudinal 
line of the body. The preoperculum (t) partakes of the same form, 
but is considerably less than the operculum, and is placed about 
midway between the eye and the posterior margin of the gill-plate. 
The clavicle (7), which is well preserved in one of the specimens, 
is a long, stout, fusiform bone, extending from above the longitudinal 
middle line of the body to the insertion of the ventral fin, and is 
well inclined thence upwards and backwards. 
The pectoral fins (¢), which are ;5, inch long, are wide and some- 
what rounded, the extremity being obtuse; they are rather large in 
proportion to the size of the body, and are situated just behind and 
below the angle of the operculum, consequently on the central lon- 
gitudinal line. They are connected with the upper portion of the 
clavicle. The remains of apparently the scapula and coracoid were 
observed in one of the specimens ; they are, however, in a crushed 
state, but seem to have been broad, flat, and short, and are arched 
towards each other. From these extend fourteen or fifteen flat and 
rather delicate brachial rays (c'), the longest of which are near the 
middle and measure rather more than + inch in length; they are 
articulated with double their number of simple fin-rays. which are 
composed of numerous joints. 
The ventral fins (d) originate in front of the ventral or thoracic 
plates, to be shortly described, and immediately behind the lower ex- 
tremity of the clavicle, and incline backwards; they are upwards of half 
an inch in length, are proportionally narrow and are sharp-pointed ; 
they have each about fourteen or fifteen rays, which are made up of 
numerous joints, and are attached to elongated narrow pelvic bones; 
but these are too much obscured to admit of complete description. 
