24 



SCANDINAVIAN FISHES. 



observations, tliat during the development of some of 

 the Acanthopterygians there occurs a juvenile period 

 which reminds us of the Ganoid type. As instances of 

 this we may give the Tholichthys stage of the Chcctodon 

 family", the CepJtalacanthits stage of the Swordfish'', and 

 the BhynchicMys stage for the Berycides''. The latter, 

 however, as they are included in the great series of the 

 Percomorph families, are themselves to be regarded as 

 similar mementoes. With this point also is connected 

 the denticulation of the preoperculum'' which appears 

 during youth and subsequently disappears, in manj^ forms 

 of the great Scomberomorph series. In these common 

 traces of an older type lies a, band of union, -which ex- 

 plains the difficulty of finding concise expressions of the 

 family characters and of referring, them to natural groups. 

 Where the history of development has not yet taught 

 us anything as to the natural relationship of the families 

 to each other, there remains nothing, except to alloAv iso- 

 lated characters to decide the point, though they may per- 

 haps lead us to construct a more or less unnatural system. 

 According to the precedent set by Gunther^ but 

 Avith those alterations which seem to be rendered neces- 

 sary b)' the attempts of later writers-^ to systematize, 

 Ave shall arrange the families of the Scandinavian Fauna 

 that belong to this division, in accordance with the views 

 that seem to us the most natural. The Acanthopterygii 

 Lysipliaryiigei seem to us most naturally suited for a 

 ])rimary classification in two great divisions, limited 

 according to the structure of the caudal and paired fins. 

 Among the latter, the ventral fins vary in situation and 

 in composition; and the pectoral exhibit a considerable 

 difference in breadth, a difference Avhich also affects the 

 shajje of the basal bones of these fins. Besides these 

 differences, there is also in most cases a difference in 

 the composition of the caudal fin, most easily exjiressed 

 in the number of the bi'anched rays of this fin. In 

 those Lysipharyngei Avhich in most otlier respects are 

 the most regular, the ventral fins are placed below the 



pectoral, or just behind the perpendicular from the base 

 of the latter fins {Acanthopterygii thoracici), and consist 

 most often of one spinous ray and five soft rays. The 

 pectoral fins are compai-atively narrow (Ac. stenohrachii), 

 and the basal bones generally narrow and shaped like 

 a sand-glass: the number of branched rays in the caudal 

 fin is comparatively larger {Ac. euryripidi). This divi- 

 sion of Lysipharyngei may be called Idiopteri' on ac- 

 count of the regularity of the structure of their fins. The 

 second division may also, it is true, possess thoracic and 

 regular ventral fins. But most commonly tliese fins 

 have fe-\\-er rays, are changed into organs of Avalking or 

 adhesion, or situated on the abdomen {Ac. ahdomhiales) 

 at some distance behind the pectoral fins, or sometimes 

 before the latter on the thront { Ac. jug ul ares). The pecto- 

 rals are generally broad at the l)ase, or their basal bones 

 at least are broad and flat (Ac. eurybrachii) or abnorm- 

 ally developed in some other Avay {pedicuJati). The caudal 

 fin has fewer branched rays'', generally less tlian 15 {Ac. 

 stenoripidi). This division we shall call AnomalopterV. 



In addition to the characters of these divisons Avhich 

 Ave have now described, there also exists a biological 

 difference betAveen them. The first division contains, 

 generally speaking, fishes of an active way of life, whether 

 they be shore-fishes, Avandering pelagic fishes, or deep- 

 sea fishes. The second division includes, on the con- 

 trary, bottom-fishes of a more quiet and sluggish Avay 

 of life. The more marked this Avay of life is, the more 

 distinctly do these characters appear; and if the mode 

 of life be changed, there may generally be observed, 

 both in the shape of the body and in the other characters, 

 an apparent transition in the direction of the other type. 



The types around Avhich most of the other Id'iopteri 

 may most conveniently be arranged in families are, in the 

 Scandinavian Fauna, the Perch and the Mackerel, Avhich 

 may therefore each give their names to one of the series 

 here described, series Avhich, from a systematical point 

 of view, are correlatiA^e to that of the Fharyngogiiathi. 



" LtJTKEN, Spol. tab. V, fig. 7 — 11. 



» GtNTHER, Journ. Mu8. Geoffr., Bd. I, p. 170 (Hcf(. 2, p. 98); LCtken, Spol, Tab. 11, fig. 11. 



' Lt)TKEN, Spol, Tab. II, fig. 4 — 7. 



■* LiJTKEN, Spol, Tab. Ill and IV. 



' Brit. Mus. Cat., Fish., Systematic Synopsis of Acantliopt. Fisb. (App. to Vol. Ill) and An Introd. to the Study of Fishes, p. 374, 

 Handb. d. Ichth., pp. 263 etc. 



f Cope, Contr. to the irhth. of the Lesser Antilles, Trans. Am. Pbil. Soc. Vol. XIV, n. ser., Art. V, p. 445. — Fitzinoer, ]'ers. 

 ciner Natiirl. Classif. d. Fische, Sitxber. Akad. Wiss. Wien, Matb. Naturv. CI., Bd. LXVII, Abtb. 1, p. 5. — Gill, Arraiig. Fam. of Fishes, 

 Smiths. Misc. Coll., vol. XI, Art. 11 (n:o 247). — Jordan & Gilrert, Syn. Fish. N. Am., Bull. U. S. Nat.. Mus. n:o 16. 



f Orthocornii thoracopteri (p. p.) Fitzingeu, 1. c, p. 28. 



* Such exceptions as Gohivs lanceolatus, for instance, clearly depend vijion tlic fact that the supporting rays of the caudal fin (at the 

 top and bottom) are also branched. 



'■ Orthocornii psetidogastropteri (p. p.) + //eterocormi acanthojiteri + Anomali pedicittati, FiTZ. 1. c. pp. 34, 39, 48. 



