1016 
SCANDINAVIAN FISHES. 
half its length, with an unbroken 0 card of teeth, which 
are straight or slightly recurved at the tip, in young 
Eels pointed, in old more obtuse. In the extreme front, 
at the tip of the snout, the bone has an expansion, 
like a vomerine head (fig. 268, D), and behind this 
point it is constricted. The form of the dental card 
follows that of the bone. Into the said constriction on 
each side is fitted the outer bone with its card of teeth, 
which resembles in composition the vomerine card, and 
extends, gradually narrowing behind, to the very cor- 
ner of the mouth, working against an exactly similar 
card on each half of the mandible. 
It is easy to perceive that the structure of the 
palatine roof and the upper jaw may give rise to the 
most conflicting interpretations. That a comprehensive 
reduction has taken place, is obvious. The inner bone 
Fig. 269. Bones of the palatine roof and jaws in Anguilla vulgaris. 
3 / 9 times the natural size. 
hm, hyomandibnlar ; hma, its anterior articulary process; limp, its 
posterior articulary process, with the end of which the operculum ar- 
ticulates; qu, quadrate; pt, entopterygoid ; mp, palato-maxillary ; mdb. 
mandible; art, its articular part; cl, its dental part. 
(pt), which serves to connect the hyomandibular and 
quadrate with the anterior part of the parasphenoid 
and with the bone which we have hitherto called the 
outer bone, cannot be explained as anything but a pte- 
rygoid. Such is the position occupied on each side of 
the palate in all the Teleosts — where these bones are 
distinct from each other — by the inner pterygoid ( en - 
topterygoideum 1. mesopterygoideum ) and the posterior 
pterygoid ( metapterygoideum ), the latter of which has 
coalesced in the. Eels, according to Owen * 6 , with the 
hyomandibular. The outer bone (mp) has received three 
interpretations: as a palatine (1), a maxillary (2), and 
an intermaxillary (3). 
The first-mentioned interpretation (1), which was 
suggested by Owen 0 , presupposes that the maxillaries 
as ivell as the intermaxillaries have disappeared in the 
process of reduction, and that the tip of the snout is 
formed, as in the Pike, by the ethmoid and vomer. 
Tendencies to such a reduction we have seen above, 
e. g. in the maxillaries of the Glanomorphs and in the 
intermaxillaries of Argentina. The hind extremity of 
the assumed palatine occupies a peculiar position, it is 
true, in relation to the lower jaw; still it is not so 
superficial and free as the extremity of the maxillaries 
in other, more typical Teleosts, and it is also joined, 
according to Jacoby, by a band of sinew to the quad- 
rate bone. 
The second explanation (2) — according to which 
the margin of the upper jaw is formed on each side by 
Fig. 270. Opercular apparatus of Anguilla vulgaris. X s / 2 . 
op, operculum; pop, preoperculum; sop, suboperculum; iop, inter- 
operculum. 
the maxillaries — was first given by Rosenthal' 4 and 
Meckel 0 , and has subsequently been adopted by Peters 
and his pupil Jacoby in Berlin, by Brattstrom 7 and 
his teacher Lilljebobg, and others. It is based on the 
presumption that palatines are wanting, and that the 
intermaxillaries, in their confluence with the ethmoid 
and vomer, form the tip of the snout. The relation 
of the assumed maxillary to the pterygoid and the ho- 
rizontal expansion inwards of its anterior part, how- 
ever, do not agree with this interpretation, nor can the 
assumed coalescence of the intermaxillaries and the 
other bones at the tip of the snout be regarded as by 
any means fully demonstrated. 
a The gap mentioned by Jacoby (1. c., p. 291) I have not been able to detect, even in young Eels 66 mm. long. 
6 Compar. Anat.. Physiol. Vertebr., vol. I, p. 122. 
c 1. c., pp. 113 and 118. 
d Tchthyotom. Tafeln , taf. XXIII, i* . 
e Syst. Vergleich. Anat., Bd II, p. 356. 
■' Om krauiet och skuldergordeln hos Murcona anguilla , Lin., disp. Ups. 1875, p. 17. 
