BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 21. AFD. IV. N:0 3. )D 
It is probable that the central disc in this specimen, 
alike the others previously found in Germany and Galicia, is 
provided on its interior surface with paired impressions of 
the gills on both sides and of the peculiar organs situated 
anteriorly on the median linie. One of these is by some authors 
regarded as a parietal eye and perhaps it corresponds with 
a prominent little tubercle on the exterior surface in the 
middle of the triangular area. 
The second specimen (P1. I, fig. 5) is a little smaller, also of 
an oval shape, but consists of only one piece. There is conse- 
quently no rostrum, nor is there any probability that there 
has been a deciduous one, as the anterior margin shows no 
indieations of a rupture. A narrow triangular space with 
irregular ridges is situated close to the anterior margin, by 
no means attalning so large a size as in the dorsal shield. 
It is highly probable that this smaller shield has been the 
ventral one of the same specimen, as it in its general shape 
so well corresponds with this, as also with those from pre- 
viously known species. 
Along with some other fragments was found, detached 
and broken into three pieces, what may be regarded as the 
shelly covering of an extremity or limb (P1. I, fig. 9—12). TItis 
plain that it is not a fragment of the dorsal shield nor of one 
of the cornua. Its exterior ridged surface is, to wit, inflected 
towards the interior surface along the lateral edges and partly 
covers it. In all probability the muscular and other organs, 
which it has covered, were in the same way sheltered on both 
sides by similar plates. It is narrow, elongated, by degrees 
tapering and ending bluntly. The surface is of the same 
glossy lustre as the other portions of the exoskeleton and is 
covered with ridges which have a nearly parallel direction 
and continue without interruption. On the interior surface 
(P1. I, fig. 12) which is quite smooth, are seen the polygonal 
partition lines of the vacuole walls and the openings of the 
minute canals. There is no evidence that it has consisted of 
more than one plate, nor that the supposed extremity has 
been covered by several plates, as the limbs of Pterichthys. 
On the slab bearing the dorsal scutum there lies a scale, 
(P1. IT, fig. 6—7) broken at one side, what shows that it has been 
a little longer than at present. It has the same glossy sur- 
face as the shields and is transversally protracted into a 
