718 
SCANDINAVIAN FISHES. 
without transverse processes; but the fourth, when its 
body is distinct from that of the third, not only pos- 
sesses a rib-like transverse process on each side, united 
by a suture to this side and both set and curved in 
the same direction as the ribs, only shorter and more 
terete than they, but also bears on its under surface 
an inner, lamellar process, set transversely and united 
to the body of the vertebra and to the transverse 
processes, pierced at the base (like an hypapophysis), 
and curved backwards and downwards behind the tip of 
the large pharyngeal .process of the occipital bone. To 
the posterior surface of this inner process of the fourth 
vertebra is attached the centre of the anterior end of 
the air-bladder, and the passage in its base receives the 
aorta and the anterior end of the kidneys. According 
to Sagemehl" this process also belongs to the fourth 
vertebra in Hydrocyon (a Characinoid) and originates 
from the ventral and partly from the lateral sides of 
the body of this vertebra 6 . In the Barbel, where, as 
we have mentioned, the body of the fourth vertebra 
coalesces with that of the third, we see, however, that 
the roots of this process lie on the anterior part of this 
composite body, thus within the limits of the third ver- 
tebra. A removal in a backward direction thus seems 
to have taken place in the rest of our Cyprinoids, an 
assumption which finds further ground in the insertion 
of the hindmost so-called acoustic bone ( malleus ) between 
this process and the true transverse process of the fourth 
vertebra to join the wall of the air-bladder. Here, as in 
the Sheat-fish (see above, p. 699), we explain the malleus 
on each side as the transformed rib of the third vertebra. 
In the Cyprinoids it is crescent-shaped or, rather, like 
the blade of a headsman’s axe, and at the inner (con- 
cave) margin is set the process whereby it articulates 
with the side of the body of the third vertebra. Its 
anterior end, which is united by a ligament to the so- 
called stapes, projects above the base of the transverse 
process of the second vertebra. This last vertebra sends 
out to the ligament just mentioned the bone which has 
been called the incus , a bonelet bifid at the base and 
with one branch articulating in a hole in the body of the 
second vertebra and the other united by a ligament to the 
same bone. The incus on each side is explained as the 
transformed rib c and neural arch of the second vertebra. 
The tivo anterior among the so-called acoustic bones, 
the stapes and claustrum, Avhich lie close to each other 
on the covering membrane of the atrium sinus imparls 
(see above, p. 699), are partly foliate in form, and are 
explained as representing on each side the othenvise Avant- 
ing neural arch and spine of the first vertebra. The se- 
cond vertebra is apparently Avithout neural spine (upper 
spinous process), but its place is taken by a covering 
bone above the spinal canal betAveen the occipital bone 
and the large neural spine of the third vertebra, Avhich 
spine is usually strengthened by coalescence Avith the 
neural spine of the fourth vertebra. 
In the structure of the head Ave shall here remark 
only the comparatively perfect development of the or- 
bital ring. Not only do the ordinary (here 4 — 8) sub- 
orbital bones surround the eye behind, beloAv, and in 
front; the eye is also protected above by a supraorbital 
bone, a covering bone on the frontal bone of each side. 
The skeleton of the Cyprinoids, Avhich as a rule 
contains a moderate number of vertebrae (40 d — 50), is 
further distinguished by the high and upright, anterior 
and upper, articular processes (zygapophyses) of the ab- 
dominal vertebrae, especially in the forepart of the trunk, 
where the top of each of these processes meets the base 
of the neural spine of the vertebra immediately in front 
or the upper part of the neural arch of this vertebra. 
The shoulder- girdle is strong. The incurved anterior mar- 
gin of the clavicle may sometimes, as in Labeo e , be de- 
veloped into a disk so broad that only a narroAv passage 
is left for the oesophagus. The coracoid bone is also as a 
rule comparatively broad, and the precoracoid bone 
ascending from the upper margin thereof, is bifid at the 
top, one branch meeting the clavicle, the other the sca- 
pula. The pelvic bones are elongated, in front bifid, 
sometimes for the greater part of their length, behind 
united by cartilage or a suture. From a morphological 
point of vieAv the articulation of the ventral fins is in- 
teresting, as Davidoff has shoAvn 7 , on account of its 
“ Morphol. Jalirb., Bd. X (1884), p. 55. 
b Sagemehl explains it as a transformed pair of ribs belonging to this vertebra. Sorensen, who calls it os suspensorium , ascribes it 
to an ossification of the wall of the air-bladder. Cf. Sagemehl’s explanation of the pharyngeal process of the occipital bone (see above). 
c Ligamentous ossification, according to Sorensen, Om Forbeninger i Svommeblceren etc., Dsk. Vid. Selsk. Ski-., 6:te Rsekke, Naturv., 
Math. Afh., B. 6, No. 2, p. 41 (sep.). The said paper did not reach me, unfortunately, until this sheet was in the press. 
d In Barbus maculatus , according to Gunther, 30. 
e Gunther, Cat., VII, p. 47. 
f Morphol. Jalirb., VI (1880), p. 404, taf. XXI, fig. 4. 
