1016 



SCANDINAVIAN FISHES. 



half its ]ono:th, with an uiil)i-<il<eii" card of twth, which 

 are straigiit or slightly recurved at the tip, in young 

 Eels pointed, in (jld more obtuse. In the extreme front, 

 at the tip of the snout, the bone has an expansion, 

 like a vomerine head (fig. :2G8, D), and behind this 

 ]ioiiit 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 

 mcst conflicting interpretations. That a comprehensive 

 reduction has taken place, is obvious. The inner bone 



Fiij. "2(59. Bones of tlie paliitinc roof nnd jaws in Anguilta vulgaris. 



'* ., times tlio niitural size. 

 Inn, liyoiiiniiilibular; hiihi, its anterior articuhiry process; limp, its 

 posterior nrticulary process, witli the end of which the opercuhim ar- 

 ticulates; i]u, quadrate; ■pt, entopterygoid ; mp, palato-inaxillary; mdb. 

 mandible; art. its arlii-ular part; d, its dental part. 



(pt),, which serves to connect the hyomandibular and 

 quadrate witii the anterior part of the parasphenoid 

 and with the bone wliich 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 othei by the inner pterygoid {en- 



toptenjgoldeum 1. mesopterygoideum) and the posterior 

 pterygoid {nietapterygoideum), the latter of which has 

 coalesced in the Eels, according to ()wen\ with the 

 hyomandibular. The outer bone (nip) lias received three 



interpretations: as a jxdafine (1), a maxillary (2), and 

 an intermaxillary (o). 



The first-mentioned interpretation (1), which was 

 suggested by Owen', jiresupposes that the maxillaries 

 as well 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 occujjies a peculiar jiosition, 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, 

 accoi'diiig to Jacoby, by a band of sinew to the quad- 

 rate bone. 



The second explanation (2) — acc(jrding to which 

 the margin of the u])per jaw is formed on each side by 



Fig. 270. Operciilar apparatus of Aihjiiilla vulijaris. X ' .,. 



op, operculum; pop, preopercvUum ; sop, subopercuhnn; iop. inter- 



opercnlum. 



the maxillaries — was fir.st given by Rosenthal' and 

 Meckel', and has subsequently been adopted by Peters 

 and his pupil Jacoby in Berlin, by Brattstrom-' and 

 his teacher Lilljeboug, and others. It is based on the 

 presum])tion that palatines are wanting, and that the 

 intermaxillaries, in their confluence ^vith the ethmoid 

 and vomer, form the tip of the snout. The relation 

 of the assumed maxillary to the pterj'goid 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 tij) of the snout be regarded as by 

 any means fully demonstrated. 



, p. 291) I have not been able to detect, 

 »1. 1, p. 122. 



" The gap mentioned by Jacoby (1. 



'' Compar. Anat.. Phijsiol. Vertebr., 



'■ 1. c, pp. 113 and 118. 



' Irhtliijutom. Tafebi, ta£. .Will, /*. 



'■ Sijst. Venjleich. Anat, Ed II. p. .350. 



■' Om kraniet ocli .ihdderijordeln ho.t ^ful^a■na anfjuilla, Li.N., disp. Ups. 187.5, p. 1 



en in young Eels 66 mm. long. 



