PERCHES. 



25 



PEKCOMOKPHI. 



The fumiUes of the I'ercomorph series, tvith scales nsuaUy ctenoid and uniformly covering the whole body, are further 

 distinfjuisheil l>y the lateral compression of the body, which is more or less deep even at the peduncle of the tail^ 

 and also ly the yeneral strength of the spinous rays in the dorsal^ anal and ventral fins. The suhorbital ring 



has no osseous connection tvith the preoperculum. 



Althouo;li \\\' h;i\(' just stated that one of the elia- 

 racters whieli (listiiiguish most of tlie foi-ms within this 

 series, namely the clenticuhi-tiou of tlie preoperculiim, 

 may appenr in the mackerel-series as a character of the 

 younger specimens, thus showing that the latter series 

 has, in this respect at least, reached a higher degree of 

 metamorphosis, still, according to established custom and 

 the precedent set I))' (Iuviek, we place the Percomorph 

 series first. It is this type that gives the clenrest idea 

 of the pei-fection of the Eleutherognates, for in it no 

 special organic system has been stunted or developed 

 at the expense of the others and thus in any respect 

 caused a distortion of the regularity of the Teleo- 

 steous form. 



'I'lie families of the Scandinavian Fauna which 

 belong to tliis series may lie distinguished by means 

 of the following scheme. 



I : Ventral lins regular, with 1 spinous and h soft rays. 

 A: Branchiostogal rays at least 5. Chin without 

 or with only rudimentary barbels. 

 a: Preorbital bone covering only the anterior 

 and superior parts of the maxillary bone 

 when the mouth is closed. 



a: A'omer with teeth Perddo'. 



fi: \omer toothless Scicniidw. 



b: Preorbital bone covering the whole of the 



maxillary bone, when the mouth is closed Spatidw. 

 B: Branchiostegal rays 4. Chin with large and 



mobile barbels MulUdce. 



II: Ventral fins with 1 spinous ray and more (or less) 



than 5 soft rays Berycida. 



Fam PERCID/E. 



Exterior bones of the head, at least the irreoperculum, jagged or denticulated. Scales denticulated. Spinousrayed 



part of the dorsal fn or the anterior dorsal fin without scales, and longer than the soft-rayed part or posterior 



dorsal fn. S/mjjle, conical teeth on the lower jaw, the intermaxillary bones, the vomer and the imlatine bones. 



The ventral fins thoracic, with one spinous and five soft rays. Chin without barbels. 



In numbei- of sjjecies the Percoid family is one of 



the largest among the Teleostei. Gunther gives in his 



Catalogue more than 700 species which must be refei-red 



to tliis f;imily according to his later opinion''. They 



belong to the salt and fresh waters of the tropical and 



temperate zones: only a few are met with north of 



the polar circle, and among these we find just those 



species wliich belong to Scandinavia,. Their geological 



age is, as far as we know, not great, but one species 



of tlu' true genus Pcrra has been found in the Miocene 



strata ;it Oeningen. Tlie genera whicli belong to the 



Scandinavian Faun;i mav be distinguished by means of 



the following .scheme: 



A: Anal lin with 2 spinous rays. (Number of 

 vertcbrEe 30 — 45: Percime) 



a: Two dorsal fins. 



a: The teeth of the jaws and palate 



equal in height (no canine teeth) Perca. 



^: Between the jaw-teeth and the palatine 

 teeth large canine teeth far apart from 



each other -- Stizostedium . 



b: One dorsal fin - Acerina 



B: Anal (in with 3 spinous rays. (Number of 

 vertebrte about 24: Serraninw) 



a: Two dorsal fins lioccus. 



b: One dorsal fin Polyjyrion. 



Each of these genera is represented in our Fauna 

 by only one species. On that account, and becau.se the 

 Scandinavian forms whicli belong to this fiimily are not 

 so numerous as to render it difficult to distinguish 

 them without anv further division of the family, we 



" Cope, (p. p.) Acanth. Ferciformes, GUntheu (p. p.) 

 * Introd. Stud. Fisli. 



Scandinavian Fishes. 



